Re: [PATCH] drm/bridge: analogix_dp: Don't return -EBUSY when msg->size is 0 in aux transaction

From	Tomasz Figa <tfiga@chromium.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] drm/bridge: analogix_dp: Don't return -EBUSY when msg->size is 0 in aux transaction
Date	2017-02-20 05:30 +0100
Message-ID	<tcNLP-8g1-1@gated-at.bofh.it> (permalink)
References	<tal7j-1Oy-13@gated-at.bofh.it> <tcMd3-78N-3@gated-at.bofh.it> <tcNsu-89s-7@gated-at.bofh.it>
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On Mon, Feb 20, 2017 at 1:04 PM, Zain Wang <wzz@rock-chips.com> wrote:
> 在 2017/2/20 10:40, Tomasz Figa 写道:
>> On Mon, Feb 13, 2017 at 6:27 PM, zain wang <wzz@rock-chips.com> wrote:
>>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
>>> b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
>>> index 303083a..5384aca 100644
>>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
>>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
>>> @@ -1162,5 +1162,5 @@ ssize_t analogix_dp_transfer(struct
>>> analogix_dp_device *dp,
>>>                   (msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_NATIVE_READ)
>>>                  msg->reply = DP_AUX_NATIVE_REPLY_ACK;
>>>
>>> -       return num_transferred > 0 ? num_transferred : -EBUSY;
>>> +       return (num_transferred == msg->size) ? num_transferred : -EBUSY;
>>
>> I might be missing something but, looking at the code, I don't see any
>> possibility of num_transferred ever being different than msg->size. To
>> be honest, it doesn't seem to even make any sense keeping the local
>> variable there, because msg->size can be simply always returned, as
>> errors are handled by jumping to aux_error label.
>
> Yeah, I agree with you.
> The better way to fix this issue is to revert the changes
> https://patchwork.kernel.org/patch/9411711/
> (returning num_transferred directly may be better here)

I think it's still not enough to clean up the code completely. It
should be just enough to remove num_transferred completely and simply
return msg->size at the end.

Best regards,
Tomasz

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Re: [PATCH] drm/bridge: analogix_dp: Don't return -EBUSY when  msg->size is 0 in aux transaction Tomasz Figa <tfiga@chromium.org> - 2017-02-20 03:50 +0100
  Re: [PATCH] drm/bridge: analogix_dp: Don't return -EBUSY when  msg->size is 0 in aux transaction Zain Wang <wzz@rock-chips.com> - 2017-02-20 05:10 +0100
    Re: [PATCH] drm/bridge: analogix_dp: Don't return -EBUSY when  msg->size is 0 in aux transaction Tomasz Figa <tfiga@chromium.org> - 2017-02-20 05:30 +0100

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