On Thu, May 3, 2018 at 11:40 AM, Boris Brezillon boris.brezillon@bootlin.com wrote:
The device might be described in the device tree but not connected to the I2C bus. Update the status property so that the DRM panel logic returns -ENODEV when someone tries to get the panel attached to this DT node.
Signed-off-by: Boris Brezillon boris.brezillon@bootlin.com
.../gpu/drm/panel/panel-raspberrypi-touchscreen.c | 35 ++++++++++++++++++++++ 1 file changed, 35 insertions(+)
diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c index 2c9c9722734f..b8fcb1acef75 100644 --- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c +++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c @@ -358,6 +358,39 @@ static const struct drm_panel_funcs rpi_touchscreen_funcs = { .get_modes = rpi_touchscreen_get_modes, };
+static void rpi_touchscreen_set_status_fail(struct i2c_client *i2c) +{
struct property *newprop;newprop = kzalloc(sizeof(*newprop), GFP_KERNEL);if (!newprop)return;newprop->name = kstrdup("status", GFP_KERNEL);if (!newprop->name)goto err;newprop->value = kstrdup("fail", GFP_KERNEL);if (!newprop->value)goto err;newprop->length = sizeof("fail");if (of_update_property(i2c->dev.of_node, newprop))goto err;
As I mentioned on irc, can you make this a common DT function.
I'm not sure if it matters that we set status to fail vs. disabled. I somewhat prefer the latter as we already have other cases and I'd rather the api not pass a string in. I can't think of any reason to distinguish the difference between fail and disabled.
/* We intentionally leak the memory we allocate here, because the new* OF property might live longer than the underlying dev, so no way* we can use devm_kzalloc() here.*/return;+err:
kfree(newprop->value);kfree(newprop->name);kfree(newprop);+}
static int rpi_touchscreen_probe(struct i2c_client *i2c, const struct i2c_device_id *id) { @@ -382,6 +415,7 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
ver = rpi_touchscreen_i2c_read(ts, REG_ID); if (ver < 0) {
rpi_touchscreen_set_status_fail(i2c);
I've thought some more about this and I still think this should be handled in the driver core or i2c core.
The reason is simple. I think the state of the system should be the same after this as if you booted with 'status = "disabled"' for this node. And that means the device should be removed completely because we don't create struct device's for disabled nodes.
Rob