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.brezil...@bootlin.com>
Cc: Rob Herring <robh...@kernel.org>
Cc: Thierry Reding <thierry.red...@gmail.com>
Cc: Daniel Vetter <dan...@ffwll.ch>
Cc: Eric Anholt <e...@anholt.net>
---
Rob, Thierry,
I know this v3 is not following your recommendations (propagate the
error to the upper layer and let the code in drivers/{base,i2c}/ handle
the reprobing of devices that previously returned EPROBE_DEFER and the
deregistration of the device that has been marked disabled), but it
addresses the problem Eric was trying to solve in a simple and
non-invasive way.
I'm all for a clean solution, but I also know this sort of rework is
likely to take time, so I'd appreciate having this patch accepted
first.
Regards,
Boris
Changes in v3:
- Do not return -ENODEV when the touchscree detection fails, so that
the DRM driver can be probed again and detect that the panel status
is "failed"
Changes in v2:
- New commit
---
.../drm/panel/panel-raspberrypi-touchscreen.c | 46 +++++++++++++++++--
1 file changed, 42 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index 2c9c9722734f..26b5576c07f9 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;
+
+ /* 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)
{
@@ -376,14 +409,13 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
if (!ts)
return -ENOMEM;
- i2c_set_clientdata(i2c, ts);
-
ts->i2c = i2c;
ver = rpi_touchscreen_i2c_read(ts, REG_ID);
if (ver < 0) {
+ rpi_touchscreen_set_status_fail(i2c);
dev_err(dev, "Atmel I2C read failed: %d\n", ver);
- return -ENODEV;
+ return 0;
}
switch (ver) {
@@ -391,10 +423,13 @@ static int rpi_touchscreen_probe(struct i2c_client *i2c,
case 0xc3: /* ver 2 */
break;
default:
+ rpi_touchscreen_set_status_fail(i2c);
dev_err(dev, "Unknown Atmel firmware revision: 0x%02x\n", ver);
- return -ENODEV;
+ return 0;
}
+ i2c_set_clientdata(i2c, ts);
+
/* Turn off at boot, so we can cleanly sequence powering on. */
rpi_touchscreen_i2c_write(ts, REG_POWERON, 0);
@@ -435,6 +470,9 @@ static int rpi_touchscreen_remove(struct i2c_client *i2c)
{
struct rpi_touchscreen *ts = i2c_get_clientdata(i2c);
+ if (!ts)
+ return 0;
+
mipi_dsi_detach(ts->dsi);
drm_panel_remove(&ts->base);
--
2.17.1
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