linux-kernel - Re: [PATCH v4 02/11] drm/bridge: it6505: fix aux operation for edid read

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Message-ID: <CAA8EJppG01kE-USS6XYp5gRwEq-hNAUY0cBLfEcHZQgP8CRTsg@mail.gmail.com>
Date: Thu, 26 Sep 2024 10:05:22 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Hermes.Wu@....com.tw
Cc: Kenneth.Hung@....com.tw, andrzej.hajda@...el.com, 
	neil.armstrong@...aro.org, rfoss@...nel.org, 
	Laurent.pinchart@...asonboard.com, jonas@...boo.se, jernej.skrabec@...il.com, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, 
	airlied@...il.com, simona@...ll.ch, angelogioacchino.delregno@...labora.com, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 02/11] drm/bridge: it6505: fix aux operation for edid read

On Thu, 26 Sept 2024 at 10:04, <Hermes.Wu@....com.tw> wrote:
>
> >On Thu, Sep 26, 2024 at 03:47:52PM GMT, Hermes Wu wrote:
> >> From: Hermes Wu <Hermes.wu@....com.tw>
> >>
> >> The EDID read operation can reach the maximum size of the AUX FIFO buffer.
> >
> >And? Commit message should describe why the change is necessary and what is being done. Just providing a statement is not enough.
> >
>
> The original AUX operation treat all reads by using data registers will be limited at 4 bytes.
> AUX operation command CMD_AUX_I2C_EDID_READ using AUX FIFO is capable of reads data by 16 bytes each time.
> It can improve speed of read EDID.

improves, rather than "can improve". Please add this to the commit message.

>
>
> >>
> >> Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver")
> >> Signed-off-by: Hermes Wu <Hermes.wu@....com.tw>
> >> ---
> >>  drivers/gpu/drm/bridge/ite-it6505.c | 8 ++++++--
> >>  1 file changed, 6 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c
> >> b/drivers/gpu/drm/bridge/ite-it6505.c
> >> index 28a8043229d3..b451d3c2ac1d 100644
> >> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> >> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> >> @@ -1078,8 +1078,11 @@ static ssize_t it6505_aux_do_transfer(struct it6505 *it6505,
> >>      int i, ret_size, ret = 0, request_size;
> >>
> >>      mutex_lock(&it6505->aux_lock);
> >> -    for (i = 0; i < size; i += 4) {
> >> -            request_size = min((int)size - i, 4);
> >> +    for (i = 0; i < size; ) {
> >> +            if (cmd == CMD_AUX_I2C_EDID_READ)
> >> +                    request_size = min_t(int, (int)size - i, AUX_FIFO_MAX_SIZE);
> >> +            else
> >> +                    request_size = min_t(int, (int)size - i, 4);
> >>              ret_size = it6505_aux_operation(it6505, cmd, address + i,
> >>                                              buffer + i, request_size,
> >>                                              reply);
> >> @@ -1088,6 +1091,7 @@ static ssize_t it6505_aux_do_transfer(struct it6505 *it6505,
> >>                      goto aux_op_err;
> >>              }
> >>
> >> +            i += request_size;
> >>              ret += ret_size;
> >>      }
> >>
> >> --
> >> 2.34.1
> >>
> >
> >--
> >With best wishes
> >Dmitry
> >
>
> BR,
> Hermes
>


-- 
With best wishes
Dmitry