Hi,
On Fri, Mar 14, 2025 at 3:42 PM Wolfram Sang
<wsa+renesas@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> From: Phong Hoang <phong.hoang.wz@xxxxxxxxxxx>
>
> Add a check to the very first register access function when attaching a
> bridge device, so we can bail out if I2C communication does not work.
>
> Signed-off-by: Phong Hoang <phong.hoang.wz@xxxxxxxxxxx>
> Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
> Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> Build tested only!
>
> Changes since v1:
>
> * rebased to v6.14-rc6
> * add Laurent's tag (Thanks!)
> * update patch description according to Tomi's suggestions (Thanks!)
>
> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index e4d9006b59f1..59508e82a991 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -696,6 +696,7 @@ static struct ti_sn65dsi86 *bridge_to_ti_sn65dsi86(struct drm_bridge *bridge)
>
> static int ti_sn_attach_host(struct auxiliary_device *adev, struct ti_sn65dsi86 *pdata)
> {
> + int ret;
> int val;
> struct mipi_dsi_host *host;
> struct mipi_dsi_device *dsi;
> @@ -720,8 +721,11 @@ static int ti_sn_attach_host(struct auxiliary_device *adev, struct ti_sn65dsi86
>
> /* check if continuous dsi clock is required or not */
> pm_runtime_get_sync(dev);
> - regmap_read(pdata->regmap, SN_DPPLL_SRC_REG, &val);
> + ret = regmap_read(pdata->regmap, SN_DPPLL_SRC_REG, &val);
> pm_runtime_put_autosuspend(dev);
> + if (ret)
> + return ret;
Seems reasonable to me. I would probably put an error message in this
case, though? I don't think regmap_read() necessarily prints an error
so it would just be a mysterious failure for why things didn't probe,
right?
This also only solves the problems for one of the 4 devices in this
file. I think the GPIO device, PWM device, and DP-AUX device will
still confusingly stick around. It's probably better to add a bogus
regmap read in ti_sn65dsi86_probe().
-Doug
