Den 20.01.2021 19.02, skrev Daniel Vetter:
On Wed, Jan 20, 2021 at 6:11 PM Noralf Trønnes noralf@tronnes.org wrote:
This adds a generic USB display driver with the intention that it can be used with future USB interfaced low end displays/adapters. The Linux gadget device driver will serve as the canonical device implementation.
The following DRM properties are supported:
- Plane rotation
- Connector TV properties
There is also support for backlight brightness exposed as a backlight device.
Display modes can be made available to the host driver either as DRM display modes or through EDID. If both are present, EDID is just passed on to userspace.
Performance is preferred over color depth, so if the device supports RGB565, DRM_CAP_DUMB_PREFERRED_DEPTH will return 16.
If the device transfer buffer can't fit an uncompressed framebuffer update, the update is split up into parts that do fit.
Optimal user experience is achieved by providing damage reports either by setting FB_DAMAGE_CLIPS on pageflips or calling DRM_IOCTL_MODE_DIRTYFB.
LZ4 compression is used if the device supports it.
The driver supports a one bit monochrome transfer format: R1. This is not implemented in the gadget driver. It is added in preparation for future monochrome e-ink displays.
The driver is MIT licensed to smooth the path for any BSD port of the driver.
v2:
- Use devm_drm_dev_alloc() and drmm_mode_config_init()
- drm_fbdev_generic_setup: Use preferred_bpp=0, 16 was a copy paste error
- The drm_backlight_helper is dropped, copy in the code
I think the backlight is still a bit problematic, since you're using kms locks within the backlight callbacks. Other display drivers use backlight within their kms locks. This means inconsistent locking rules, which upsets lockdep.
Since you're already handling brightness as a special case in many places I don't think it's a big shuffle:
- add a mutex to the connector struct
- move brightness value to connector struct, out of the connector_state
- use the new mutex to protect backlight state both from modeset side
(if needed, I'm not entirely sure about that) and the backlight side
It's not enough to store the value I need to send it to the device as well. Currently I send the entire state each time there's a change. To continue that I would need to keep a copy of the state that I can use when brightness changes. Or I can treat backlight as an exception and add a USB control request just for backlight.
There is some special treatment of the backlight in the driver, but I would really like to handle the backlight brightness through the atomic machinery. I want to avoid special treatment of backlight in the USB protocol.
I can avoid the lockdep problem by letting a worker commit the state and schedule it from the backlight update callback. I'll do that unless you see other issues with that approach.
Is it ok to take the connection_mutex lock in the get_brightness callback to get to the connector state and the brightness value?
i915 takes that lock in intel_backlight_device_update_status() and intel_backlight_device_get_brightness().
Some more things below, but in general I'd say Acked-by: Daniel Vetter <daniel.vetter> fwiw (probably not so much).
Thanks for taking a look, much appreciated.
Noralf.
diff --git a/drivers/gpu/drm/gud/gud_connector.c b/drivers/gpu/drm/gud/gud_connector.c new file mode 100644 index 000000000000..a4b9bbf48e19 --- /dev/null +++ b/drivers/gpu/drm/gud/gud_connector.c @@ -0,0 +1,722 @@ +// SPDX-License-Identifier: MIT +/*
- Copyright 2020 Noralf Trønnes
- */
+#include <linux/backlight.h>
+#include <drm/drm_atomic.h> +#include <drm/drm_atomic_state_helper.h> +#include <drm/drm_connector.h> +#include <drm/drm_drv.h> +#include <drm/drm_encoder.h> +#include <drm/drm_file.h> +#include <drm/drm_modeset_helper_vtables.h> +#include <drm/drm_print.h> +#include <drm/drm_probe_helper.h> +#include <drm/drm_simple_kms_helper.h> +#include <drm/gud.h>
+#include "gud_internal.h"
+struct gud_connector {
struct drm_connector connector;struct drm_encoder encoder;struct backlight_device *backlight;/* Supported properties */u16 *properties;unsigned int num_properties;/* Initial gadget tv state if applicable, applied on state reset */struct drm_tv_connector_state initial_tv_state;/** Initial gadget backlight brightness if applicable, applied on state reset.* The value -ENODEV is used to signal no backlight.*/int initial_brightness;unsigned int num_modes;size_t edid_len;+};
+static inline struct gud_connector *to_gud_connector(struct drm_connector *connector) +{
return container_of(connector, struct gud_connector, connector);+}
+static int gud_connector_backlight_update_status(struct backlight_device *bd) +{
struct drm_connector *connector = bl_get_data(bd);struct drm_connector_state *connector_state;struct drm_device *dev = connector->dev;struct drm_modeset_acquire_ctx ctx;struct drm_atomic_state *state;int ret;state = drm_atomic_state_alloc(dev);if (!state)return -ENOMEM;drm_modeset_acquire_init(&ctx, 0);state->acquire_ctx = &ctx;+retry:
connector_state = drm_atomic_get_connector_state(state, connector);if (IS_ERR(connector_state)) {ret = PTR_ERR(connector_state);goto out;}/* Reuse tv.brightness to avoid having to subclass */connector_state->tv.brightness = bd->props.brightness;ret = drm_atomic_commit(state);+out:
if (ret == -EDEADLK) {drm_atomic_state_clear(state);drm_modeset_backoff(&ctx);goto retry;}drm_atomic_state_put(state);drm_modeset_drop_locks(&ctx);drm_modeset_acquire_fini(&ctx);return ret;+}
+static int gud_connector_backlight_get_brightness(struct backlight_device *bd) +{
struct drm_connector *connector = bl_get_data(bd);struct drm_device *dev = connector->dev;int brightness;drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);brightness = connector->state->tv.brightness;drm_modeset_unlock(&dev->mode_config.connection_mutex);return brightness;+}
+static const struct backlight_ops gud_connector_backlight_ops = {
.get_brightness = gud_connector_backlight_get_brightness,.update_status = gud_connector_backlight_update_status,+};
+static int gud_connector_backlight_register(struct gud_connector *gconn) +{
struct drm_connector *connector = &gconn->connector;struct backlight_device *bd;const char *name;const struct backlight_properties props = {.type = BACKLIGHT_RAW,.scale = BACKLIGHT_SCALE_NON_LINEAR,.max_brightness = 100,};name = kasprintf(GFP_KERNEL, "card%d-%s-backlight",connector->dev->primary->index, connector->name);if (!name)return -ENOMEM;bd = backlight_device_register(name, connector->kdev, connector,&gud_connector_backlight_ops, &props);kfree(name);if (IS_ERR(bd))return PTR_ERR(bd);gconn->backlight = bd;return 0;+}
+static int gud_connector_status_request(struct drm_connector *connector) +{
struct gud_connector *gconn = to_gud_connector(connector);struct gud_device *gdrm = to_gud_device(connector->dev);struct gud_connector_status_req req;u16 num_modes, edid_len;int ret;ret = gud_usb_get(gdrm, GUD_REQ_GET_CONNECTOR_STATUS,connector->index, &req, sizeof(req));if (ret)return ret;switch (req.status & GUD_CONNECTOR_STATUS_CONNECTED_MASK) {case GUD_CONNECTOR_STATUS_DISCONNECTED:ret = connector_status_disconnected;break;case GUD_CONNECTOR_STATUS_CONNECTED:ret = connector_status_connected;break;default:ret = connector_status_unknown;break;};num_modes = le16_to_cpu(req.num_modes);edid_len = le16_to_cpu(req.edid_len);if (edid_len % EDID_LENGTH) {drm_err(connector->dev, "%s: Invalid EDID size: %u\n", connector->name, edid_len);edid_len = 0;}if (req.status & GUD_CONNECTOR_STATUS_CHANGED ||gconn->num_modes != num_modes || gconn->edid_len != edid_len)connector->epoch_counter += 1;gconn->num_modes = num_modes;gconn->edid_len = edid_len;if (!num_modes && !edid_len && ret != connector_status_disconnected)drm_dbg_kms(connector->dev, "%s: No modes or EDID.\n", connector->name);return ret;+}
+static int gud_connector_detect(struct drm_connector *connector,
struct drm_modeset_acquire_ctx *ctx, bool force)+{
struct gud_device *gdrm = to_gud_device(connector->dev);int idx, ret;if (!drm_dev_enter(connector->dev, &idx))return connector_status_disconnected;if (force) {ret = gud_usb_set(gdrm, GUD_REQ_SET_CONNECTOR_FORCE_DETECT,connector->index, NULL, 0);if (ret) {ret = connector_status_unknown;goto exit;}}ret = gud_connector_status_request(connector);if (ret < 0)ret = connector_status_unknown;+exit:
drm_dev_exit(idx);return ret;+}
+struct gud_connector_get_edid_ctx {
struct gud_connector *gconn;void *buf;+};
+static int gud_connector_get_edid_block(void *data, u8 *buf, unsigned int block, size_t len) +{
struct gud_connector_get_edid_ctx *ctx = data;struct gud_connector *gconn = ctx->gconn;size_t start = block * EDID_LENGTH;if (start + len > gconn->edid_len)return -1;if (!block) {struct gud_device *gdrm = to_gud_device(gconn->connector.dev);int ret;/* Check because drm_do_get_edid() will retry on failure */if (!ctx->buf)ctx->buf = kmalloc(gconn->edid_len, GFP_KERNEL);if (!ctx->buf)return -1;ret = gud_usb_get(gdrm, GUD_REQ_GET_CONNECTOR_EDID, gconn->connector.index,ctx->buf, gconn->edid_len);if (ret)return -1;}memcpy(buf, ctx->buf + start, len);return 0;+}
+static int gud_connector_get_modes(struct drm_connector *connector) +{
struct gud_connector *gconn = to_gud_connector(connector);struct gud_device *gdrm = to_gud_device(connector->dev);struct gud_connector_get_edid_ctx edid_ctx = {.gconn = gconn,};struct gud_display_mode_req *reqmodes = NULL;unsigned int i, num_modes = 0;struct edid *edid = NULL;bool edid_override;int idx, ret;if (!drm_dev_enter(connector->dev, &idx))return 0;if (connector->force) {ret = gud_connector_status_request(connector);if (ret < 0)goto out;}edid = drm_do_get_edid(connector, gud_connector_get_edid_block, &edid_ctx);edid_override = edid && !edid_ctx.buf;kfree(edid_ctx.buf);drm_connector_update_edid_property(connector, edid);if (!gconn->num_modes || edid_override) {num_modes = drm_add_edid_modes(connector, edid);goto out;}reqmodes = kmalloc_array(gconn->num_modes, sizeof(*reqmodes), GFP_KERNEL);if (!reqmodes)goto out;ret = gud_usb_get(gdrm, GUD_REQ_GET_CONNECTOR_MODES, connector->index,reqmodes, gconn->num_modes * sizeof(*reqmodes));if (ret)goto out;for (i = 0; i < gconn->num_modes; i++) {struct drm_display_mode *mode;mode = drm_mode_create(connector->dev);if (!mode)goto out;gud_to_display_mode(mode, &reqmodes[i]);drm_mode_probed_add(connector, mode);num_modes++;}+out:
kfree(reqmodes);kfree(edid);drm_dev_exit(idx);return num_modes;+}
+static int gud_connector_atomic_check(struct drm_connector *connector,
struct drm_atomic_state *state)+{
struct drm_connector_state *new_state;struct drm_crtc_state *new_crtc_state;struct drm_connector_state *old_state;new_state = drm_atomic_get_new_connector_state(state, connector);if (!new_state->crtc)return 0;old_state = drm_atomic_get_old_connector_state(state, connector);new_crtc_state = drm_atomic_get_new_crtc_state(state, new_state->crtc);if (old_state->tv.margins.left != new_state->tv.margins.left ||old_state->tv.margins.right != new_state->tv.margins.right ||old_state->tv.margins.top != new_state->tv.margins.top ||old_state->tv.margins.bottom != new_state->tv.margins.bottom ||old_state->tv.mode != new_state->tv.mode ||old_state->tv.brightness != new_state->tv.brightness ||old_state->tv.contrast != new_state->tv.contrast ||old_state->tv.flicker_reduction != new_state->tv.flicker_reduction ||old_state->tv.overscan != new_state->tv.overscan ||old_state->tv.saturation != new_state->tv.saturation ||old_state->tv.hue != new_state->tv.hue)new_crtc_state->connectors_changed = true;return 0;+}
+static const struct drm_connector_helper_funcs gud_connector_helper_funcs = {
.detect_ctx = gud_connector_detect,.get_modes = gud_connector_get_modes,.atomic_check = gud_connector_atomic_check,+};
+static int gud_connector_late_register(struct drm_connector *connector) +{
struct gud_connector *gconn = to_gud_connector(connector);if (gconn->initial_brightness < 0)return 0;return gud_connector_backlight_register(gconn);+}
+static void gud_connector_early_unregister(struct drm_connector *connector) +{
struct gud_connector *gconn = to_gud_connector(connector);backlight_device_unregister(gconn->backlight);+}
+static void gud_connector_destroy(struct drm_connector *connector) +{
struct gud_connector *gconn = to_gud_connector(connector);drm_connector_cleanup(connector);kfree(gconn->properties);kfree(gconn);+}
+static void gud_connector_reset(struct drm_connector *connector) +{
struct gud_connector *gconn = to_gud_connector(connector);drm_atomic_helper_connector_reset(connector);connector->state->tv = gconn->initial_tv_state;/* Set margins from command line */drm_atomic_helper_connector_tv_reset(connector);if (gconn->initial_brightness >= 0)connector->state->tv.brightness = gconn->initial_brightness;+}
+static const struct drm_connector_funcs gud_connector_funcs = {
.fill_modes = drm_helper_probe_single_connector_modes,.late_register = gud_connector_late_register,.early_unregister = gud_connector_early_unregister,.destroy = gud_connector_destroy,.reset = gud_connector_reset,.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,+};
+/*
- The tv.mode property is shared among the connectors and its enum names are
- driver specific. This means that if more than one connector uses tv.mode,
- the enum names has to be the same.
- */
+static int gud_connector_add_tv_mode(struct gud_device *gdrm,
struct drm_connector *connector, u64 val)+{
unsigned int i, num_modes;const char **modes;size_t buf_len;char *buf;int ret;num_modes = val >> GUD_CONNECTOR_TV_MODE_NUM_SHIFT;if (!num_modes)return -EINVAL;buf_len = num_modes * GUD_CONNECTOR_TV_MODE_NAME_LEN;modes = kmalloc_array(num_modes, sizeof(*modes), GFP_KERNEL);buf = kmalloc(buf_len, GFP_KERNEL);if (!modes || !buf) {ret = -ENOMEM;goto free;}ret = gud_usb_get(gdrm, GUD_REQ_GET_CONNECTOR_TV_MODE_VALUES,connector->index, buf, buf_len);if (ret)goto free;for (i = 0; i < num_modes; i++)modes[i] = &buf[i * GUD_CONNECTOR_TV_MODE_NAME_LEN];ret = drm_mode_create_tv_properties(connector->dev, num_modes, modes);+free:
kfree(modes);kfree(buf);return ret;+}
+static struct drm_property * +gud_connector_property_lookup(struct drm_connector *connector, u16 prop) +{
struct drm_mode_config *config = &connector->dev->mode_config;switch (prop) {case GUD_PROPERTY_TV_LEFT_MARGIN:return config->tv_left_margin_property;case GUD_PROPERTY_TV_RIGHT_MARGIN:return config->tv_right_margin_property;case GUD_PROPERTY_TV_TOP_MARGIN:return config->tv_top_margin_property;case GUD_PROPERTY_TV_BOTTOM_MARGIN:return config->tv_bottom_margin_property;case GUD_PROPERTY_TV_MODE:return config->tv_mode_property;case GUD_PROPERTY_TV_BRIGHTNESS:return config->tv_brightness_property;case GUD_PROPERTY_TV_CONTRAST:return config->tv_contrast_property;case GUD_PROPERTY_TV_FLICKER_REDUCTION:return config->tv_flicker_reduction_property;case GUD_PROPERTY_TV_OVERSCAN:return config->tv_overscan_property;case GUD_PROPERTY_TV_SATURATION:return config->tv_saturation_property;case GUD_PROPERTY_TV_HUE:return config->tv_hue_property;default:return ERR_PTR(-EINVAL);}+}
+static unsigned int *gud_connector_tv_state_val(u16 prop, struct drm_tv_connector_state *state) +{
switch (prop) {case GUD_PROPERTY_TV_LEFT_MARGIN:return &state->margins.left;case GUD_PROPERTY_TV_RIGHT_MARGIN:return &state->margins.right;case GUD_PROPERTY_TV_TOP_MARGIN:return &state->margins.top;case GUD_PROPERTY_TV_BOTTOM_MARGIN:return &state->margins.bottom;case GUD_PROPERTY_TV_MODE:return &state->mode;case GUD_PROPERTY_TV_BRIGHTNESS:return &state->brightness;case GUD_PROPERTY_TV_CONTRAST:return &state->contrast;case GUD_PROPERTY_TV_FLICKER_REDUCTION:return &state->flicker_reduction;case GUD_PROPERTY_TV_OVERSCAN:return &state->overscan;case GUD_PROPERTY_TV_SATURATION:return &state->saturation;case GUD_PROPERTY_TV_HUE:return &state->hue;default:return ERR_PTR(-EINVAL);}+}
+static int gud_connector_add_properties(struct gud_device *gdrm, struct gud_connector *gconn,
unsigned int num_properties)+{
struct drm_device *drm = &gdrm->drm;struct drm_connector *connector = &gconn->connector;struct gud_property_req *properties;unsigned int i;int ret;gconn->properties = kcalloc(num_properties, sizeof(*gconn->properties), GFP_KERNEL);if (!gconn->properties)return -ENOMEM;properties = kcalloc(num_properties, sizeof(*properties), GFP_KERNEL);if (!properties)return -ENOMEM;ret = gud_usb_get(gdrm, GUD_REQ_GET_CONNECTOR_PROPERTIES, connector->index,properties, num_properties * sizeof(*properties));if (ret)goto out;for (i = 0; i < num_properties; i++) {u16 prop = le16_to_cpu(properties[i].prop);u64 val = le64_to_cpu(properties[i].val);struct drm_property *property;unsigned int *state_val;drm_dbg(drm, "property: %u = %llu(0x%llx)\n", prop, val, val);switch (prop) {case GUD_PROPERTY_TV_LEFT_MARGIN:fallthrough;case GUD_PROPERTY_TV_RIGHT_MARGIN:fallthrough;case GUD_PROPERTY_TV_TOP_MARGIN:fallthrough;case GUD_PROPERTY_TV_BOTTOM_MARGIN:ret = drm_mode_create_tv_margin_properties(drm);if (ret)goto out;break;case GUD_PROPERTY_TV_MODE:ret = gud_connector_add_tv_mode(gdrm, connector, val);if (ret)goto out;val = val & (BIT(GUD_CONNECTOR_TV_MODE_NUM_SHIFT) - 1);break;case GUD_PROPERTY_TV_BRIGHTNESS:fallthrough;case GUD_PROPERTY_TV_CONTRAST:fallthrough;case GUD_PROPERTY_TV_FLICKER_REDUCTION:fallthrough;case GUD_PROPERTY_TV_OVERSCAN:fallthrough;case GUD_PROPERTY_TV_SATURATION:fallthrough;case GUD_PROPERTY_TV_HUE:/* This is a no-op if already added. */ret = drm_mode_create_tv_properties(drm, 0, NULL);if (ret)goto out;break;case GUD_PROPERTY_BACKLIGHT_BRIGHTNESS:if (val > 100) {ret = -EINVAL;goto out;}gconn->initial_brightness = val;break;default:/* New ones might show up in future devices, skip those we don't know. */drm_dbg(drm, "Unknown property: %u\n", prop);continue;}gconn->properties[gconn->num_properties++] = prop;if (prop == GUD_PROPERTY_BACKLIGHT_BRIGHTNESS)continue; /* not a DRM property */property = gud_connector_property_lookup(connector, prop);if (WARN_ON(IS_ERR(property)))continue;state_val = gud_connector_tv_state_val(prop, &gconn->initial_tv_state);if (WARN_ON(IS_ERR(state_val)))continue;*state_val = val;drm_object_attach_property(&connector->base, property, 0);}+out:
kfree(properties);return ret;+}
+int gud_connector_fill_properties(struct drm_connector *connector,
struct drm_connector_state *connector_state,struct gud_property_req *properties)+{
struct gud_connector *gconn;unsigned int i;gconn = to_gud_connector(connector);/* Only interested in the count? */if (!connector_state)return gconn->num_properties;for (i = 0; i < gconn->num_properties; i++) {u16 prop = gconn->properties[i];u64 val;if (prop == GUD_PROPERTY_BACKLIGHT_BRIGHTNESS) {val = connector_state->tv.brightness;} else {unsigned int *state_val;state_val = gud_connector_tv_state_val(prop, &connector_state->tv);if (WARN_ON_ONCE(IS_ERR(state_val)))return PTR_ERR(state_val);val = *state_val;}properties[i].prop = cpu_to_le16(prop);properties[i].val = cpu_to_le64(val);}return gconn->num_properties;+}
+int gud_connector_create(struct gud_device *gdrm, unsigned int index) +{
struct gud_connector_descriptor_req desc;struct drm_device *drm = &gdrm->drm;struct gud_connector *gconn;struct drm_connector *connector;struct drm_encoder *encoder;int ret, connector_type;u32 flags;ret = gud_usb_get(gdrm, GUD_REQ_GET_CONNECTOR, index, &desc, sizeof(desc));if (ret)return ret;gconn = kzalloc(sizeof(*gconn), GFP_KERNEL);Would be nice to do that with drmm_, but we don't have the drmm_connector_alloc wrapper yet.
if (!gconn)return -ENOMEM;gconn->initial_brightness = -ENODEV;flags = le32_to_cpu(desc.flags);connector = &gconn->connector;drm_dbg(drm, "Connector: index=%u type=%u flags=0x%x num_properties=%u\n",index, desc.connector_type, flags, desc.num_properties);switch (desc.connector_type) {case GUD_CONNECTOR_TYPE_PANEL:connector_type = DRM_MODE_CONNECTOR_USB;break;case GUD_CONNECTOR_TYPE_VGA:connector_type = DRM_MODE_CONNECTOR_VGA;break;case GUD_CONNECTOR_TYPE_DVI:connector_type = DRM_MODE_CONNECTOR_DVID;break;case GUD_CONNECTOR_TYPE_COMPOSITE:connector_type = DRM_MODE_CONNECTOR_Composite;break;case GUD_CONNECTOR_TYPE_SVIDEO:connector_type = DRM_MODE_CONNECTOR_SVIDEO;break;case GUD_CONNECTOR_TYPE_COMPONENT:connector_type = DRM_MODE_CONNECTOR_Component;break;case GUD_CONNECTOR_TYPE_DISPLAYPORT:connector_type = DRM_MODE_CONNECTOR_DisplayPort;break;case GUD_CONNECTOR_TYPE_HDMI:connector_type = DRM_MODE_CONNECTOR_HDMIA;break;default: /* future types */connector_type = DRM_MODE_CONNECTOR_USB;break;};drm_connector_helper_add(connector, &gud_connector_helper_funcs);ret = drm_connector_init(drm, connector, &gud_connector_funcs, connector_type);if (ret) {kfree(connector);return ret;}if (WARN_ON(connector->index != index))return -EINVAL;if (flags & GUD_CONNECTOR_FLAGS_POLL_STATUS)connector->polled = (DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT);if (flags & GUD_CONNECTOR_FLAGS_INTERLACE)connector->interlace_allowed = true;if (flags & GUD_CONNECTOR_FLAGS_DOUBLESCAN)connector->doublescan_allowed = true;if (desc.num_properties) {ret = gud_connector_add_properties(gdrm, gconn, desc.num_properties);if (ret) {dev_err(drm->dev, "Failed to add connector/%u properties\n", index);return ret;}}/* The first connector is attached to the existing simple pipe encoder */if (!connector->index) {encoder = &gdrm->pipe.encoder;} else {encoder = &gconn->encoder;ret = drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_NONE);if (ret)return ret;encoder->possible_crtcs = 1;}return drm_connector_attach_encoder(connector, encoder);+}