Re: [PATCH v2] drm/bridge: ps8640: propagate AUX transfer register errors

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 29 Jul 2026, Doug Anderson <dianders@chromium.org> wrote:
> Hi,
>
> On Mon, Jul 27, 2026 at 4:40 AM Jani Nikula <jani.nikula@linux.intel.com> wrote:
>>
>> On Thu, 23 Jul 2026, Pengpeng Hou <pengpeng@iscas.ac.cn> wrote:
>> > ps8640_aux_transfer_msg() programs the AUX address registers, starts the
>> > AUX transfer, waits for SWAUX_SEND to clear, and reads the AUX status
>> > register. Several of those regmap operations have return values, but the
>> > function only checks a stale ret after the status read.
>> >
>> > Propagate failures from the address write, transfer start, completion
>> > poll, and status read. This avoids returning a transfer length when the
>> > bridge register transaction or AUX completion wait failed.
>> >
>> > Fixes: 13afcdd7277e ("drm/bridge: parade-ps8640: Add support for AUX channel")
>> > Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
>> > ---
>> > Changes since v1: https://lore.kernel.org/all/20260623060635.16064-1-pengpeng@iscas.ac.cn/
>> > - include the AUX address and length in the address-write diagnostic
>> > - describe poll failures without assuming that every error is a timeout
>> > - add the Fixes tag suggested by Doug
>> > - rebase onto the current drm-misc-next tree
>> >
>> >  drivers/gpu/drm/bridge/parade-ps8640.c | 27 +++++++++++++++++++++------
>> >  1 file changed, 21 insertions(+), 6 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
>> > index 96332721cb69..56b48f8feab6 100644
>> > --- a/drivers/gpu/drm/bridge/parade-ps8640.c
>> > +++ b/drivers/gpu/drm/bridge/parade-ps8640.c
>> > @@ -257,8 +257,14 @@ static ssize_t ps8640_aux_transfer_msg(struct drm_dp_aux *aux,
>> >       addr_len[PAGE0_SWAUX_LENGTH - base] = (len == 0) ? SWAUX_NO_PAYLOAD :
>> >                                             ((len - 1) & SWAUX_LENGTH_MASK);
>> >
>> > -     regmap_bulk_write(map, PAGE0_SWAUX_ADDR_7_0, addr_len,
>> > -                       ARRAY_SIZE(addr_len));
>> > +     ret = regmap_bulk_write(map, PAGE0_SWAUX_ADDR_7_0, addr_len,
>> > +                             ARRAY_SIZE(addr_len));
>> > +     if (ret) {
>> > +             DRM_DEV_ERROR(dev,
>>
>> DRM_DEV_ERROR() is deprecated in favour of drm_err() or dev_err().
>
> Good point. I'm inclined to land this anyway, though, since this is
> nominally a bugfix and it matches the error printing in the rest of
> the function. Any objections? It would be a nice future cleanup to fix
> the error printing in this driver overall to use the non-deprecated
> functions...

Up to you.

BR,
Jani.


-- 
Jani Nikula, Intel