Hi Sam,
On Sun, Aug 16, 2020 at 09:46:30AM +0200, Sam Ravnborg wrote:
On Thu, Aug 13, 2020 at 04:29:10AM +0300, Laurent Pinchart wrote:
A new bus-width DT property has been introduced in the bindings to allow overriding the bus width. Support it.
Signed-off-by: Laurent Pinchart laurent.pinchart@ideasonboard.com
We already reads the bus-width in following files in drm: atmel-hlcdc/atmel_hlcdc_output.c bridge/ti-tfp410.c
So this calls for a common helper to do this like:
int drm_of_bus_fmt(const struct device_node *ep) { }
This helper could then read bus-width, data-shift (if relevant) and return the relevant bus format.
I can see that bridge/ti-tfp410.c assumes 12 equals MEDIA_BUS_FMT_RGB888_2X12_LE where as mxsfb assumes 12 is MEDIA_BUS_FMT_RGB444_1X12. I do not know why neither how to handle this difference. Maybe this is something to do with DVI as this is what tfp410 seems to support.
I think the mapping from bus width to format is device-specific, I'm not sure a common helper is possible.
And now that I think about this, I wonder if data-shift = <2> wouldn't be a better option than bus-width = <24>, as a 18-bpp panel will always be connected with 18 lines, not 24. One issue, however, is that for the 565 case, I'd need a different data-shift value for R/B and for G, which isn't possible. I don't think that turning data-shift into a multi-integers property is worth it though. Given that DT properties are interpreted in the context of a particular binding using bus-width could be fine here, but I'm open to better alternatives if someone has a good proposal.
drivers/gpu/drm/mxsfb/mxsfb_drv.c | 26 ++++++++++++++++++++++++++ drivers/gpu/drm/mxsfb/mxsfb_drv.h | 2 ++ drivers/gpu/drm/mxsfb/mxsfb_kms.c | 8 ++++++-- 3 files changed, 34 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c index 8c549c3931af..fab3aae8cf73 100644 --- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c +++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c @@ -95,10 +95,36 @@ static int mxsfb_attach_bridge(struct mxsfb_drm_private *mxsfb) { struct drm_device *drm = mxsfb->drm; struct drm_connector_list_iter iter;
struct device_node *ep; struct drm_panel *panel; struct drm_bridge *bridge;
u32 bus_width = 0; int ret;
ep = of_graph_get_endpoint_by_regs(drm->dev->of_node, 0, 0);
if (!ep)
return -ENODEV;of_property_read_u32(ep, "bus-width", &bus_width);
of_node_put(ep);
switch (bus_width) {
case 16:
mxsfb->bus_format = MEDIA_BUS_FMT_RGB565_1X16;break;case 18:
mxsfb->bus_format = MEDIA_BUS_FMT_RGB666_1X18;break;case 24:
mxsfb->bus_format = MEDIA_BUS_FMT_RGB888_1X24;break;case 0:
break;default:
DRM_DEV_ERROR(drm->dev, "Invalid bus-width %u", bus_width);return -ENODEV;}
ret = drm_of_find_panel_or_bridge(drm->dev->of_node, 0, 0, &panel, &bridge); if (ret)
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.h b/drivers/gpu/drm/mxsfb/mxsfb_drv.h index 399d23e91ed1..c4f7a8a0c891 100644 --- a/drivers/gpu/drm/mxsfb/mxsfb_drv.h +++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.h @@ -32,6 +32,8 @@ struct mxsfb_drm_private { struct clk *clk_axi; struct clk *clk_disp_axi;
- u32 bus_format;
- struct drm_device *drm; struct { struct drm_plane primary;
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c index b721b8b262ce..6d512f346918 100644 --- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c +++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c @@ -50,11 +50,15 @@ static void mxsfb_set_formats(struct mxsfb_drm_private *mxsfb) { struct drm_device *drm = mxsfb->drm; const u32 format = mxsfb->crtc.primary->state->fb->format->format;
- u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
- u32 bus_format; u32 ctrl, ctrl1;
- if (mxsfb->connector->display_info.num_bus_formats)
if (mxsfb->bus_format)
bus_format = mxsfb->bus_format;else if (mxsfb->connector->display_info.num_bus_formats) bus_format = mxsfb->connector->display_info.bus_formats[0];
else
bus_format = MEDIA_BUS_FMT_RGB888_1X24;DRM_DEV_DEBUG_DRIVER(drm->dev, "Using bus_format: 0x%08X\n", bus_format);