drm/msm/dsi: fix error checks and return values for DSI xmit functions

[Dmitry Baryshkov]

On Sat, 16 Apr 2022 at 12:12, Marijn Suijten
<marijn.suijten at somainline.org> wrote:
>
> Hi Dmitry,
>
> On 2022-04-02 02:11:04, Dmitry Baryshkov wrote:
> > As noticed by Dan ([1] an the followup thread) there are multiple issues
> > with the return values for MSM DSI command transmission callback. In
> > the error case it can easily return a positive value when it should
> > have returned a proper error code.
> >
> > This commits attempts to fix these issues both in TX and in RX paths.
> >
> > [1]: https://lore.kernel.org/linux-arm-msm/20211001123617.GH2283@kili/
> >
> > Fixes: a689554ba6ed ("drm/msm: Initial add DSI connector support")
> > Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> > Reviewed-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
>
> Thank you for your patience waiting for the requested tests; this patch
> seems to have no adverse effect on our cmdmode panels.
>
> Tested-by: Marijn Suijten <marijn.suijten at somainline.org>
>
> On the following devices:
> - Sony Xperia X (Loire Suzu, MSM8976), on Linux 5.17;
> - Sony Xperia 10 II (Seine PDX201, SM6125), on -next 20220318;
> - Sony Xperia XA2 Ultra (Nile Discovery, SDM630), on Linux 5.16.
>
> Apologies for the older kernel versions, that's what happens when having
> too many patches to dig through and too little hobby time to send them.
> Let me know if there's a patch dependency that you like to be included.

Thank you for the confirmation! No, no hidden dependencies.

>
> - Marijn
>
> > ---
> >  drivers/gpu/drm/msm/dsi/dsi_host.c | 21 ++++++++++++++-------
> >  1 file changed, 14 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > index d51e70fab93d..8925f60fd9ec 100644
> > --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> > +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> > @@ -1341,10 +1341,10 @@ static int dsi_cmds2buf_tx(struct msm_dsi_host *msm_host,
> >                       dsi_get_bpp(msm_host->format) / 8;
> >
> >       len = dsi_cmd_dma_add(msm_host, msg);
> > -     if (!len) {
> > +     if (len < 0) {
> >               pr_err("%s: failed to add cmd type = 0x%x\n",
> >                       __func__,  msg->type);
> > -             return -EINVAL;
> > +             return len;
> >       }
> >
> >       /* for video mode, do not send cmds more than
> > @@ -1363,10 +1363,14 @@ static int dsi_cmds2buf_tx(struct msm_dsi_host *msm_host,
> >       }
> >
> >       ret = dsi_cmd_dma_tx(msm_host, len);
> > -     if (ret < len) {
> > -             pr_err("%s: cmd dma tx failed, type=0x%x, data0=0x%x, len=%d\n",
> > -                     __func__, msg->type, (*(u8 *)(msg->tx_buf)), len);
> > -             return -ECOMM;
> > +     if (ret < 0) {
> > +             pr_err("%s: cmd dma tx failed, type=0x%x, data0=0x%x, len=%d, ret=%d\n",
> > +                     __func__, msg->type, (*(u8 *)(msg->tx_buf)), len, ret);
> > +             return ret;
> > +     } else if (ret < len) {
> > +             pr_err("%s: cmd dma tx failed, type=0x%x, data0=0x%x, ret=%d len=%d\n",
> > +                     __func__, msg->type, (*(u8 *)(msg->tx_buf)), ret, len);
> > +             return -EIO;
> >       }
> >
> >       return len;
> > @@ -2092,9 +2096,12 @@ int msm_dsi_host_cmd_rx(struct mipi_dsi_host *host,
> >               }
> >
> >               ret = dsi_cmds2buf_tx(msm_host, msg);
> > -             if (ret < msg->tx_len) {
> > +             if (ret < 0) {
> >                       pr_err("%s: Read cmd Tx failed, %d\n", __func__, ret);
> >                       return ret;
> > +             } else if (ret < msg->tx_len) {
> > +                     pr_err("%s: Read cmd Tx failed, too short: %d\n", __func__, ret);
> > +                     return -ECOMM;
> >               }
> >
> >               /*



-- 
With best wishes
Dmitry