linux-kernel - Re: [PATCH v2] drm/msm/dsi: Fix the releasing of resources in error path in 'dsi_bus_clk

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Date:   Sun, 26 Feb 2017 10:25:03 -0500
From:   Rob Clark <robdclark@...il.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     David Airlie <airlied@...ux.ie>,
        Archit Taneja <architt@...eaurora.org>,
        Hai Li <hali@...eaurora.org>,
        Wei Yongjun <yongjun_wei@...ndmicro.com.cn>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        freedreno@...ts.freedesktop.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v2] drm/msm/dsi: Fix the releasing of resources in error
 path in 'dsi_bus_clk_enable()'

On Sun, Feb 26, 2017 at 7:10 AM, Christophe JAILLET
<christophe.jaillet@...adoo.fr> wrote:
> If a 'clk_prepare_enable()' fails, then we need to disable_unprepare the
> clk already handled.
>
> With the current implemenatation, we try to do that on the clk that has
> triggered the error, which is a no-op and leave msm_host->bus_clks[0]
> untouched.
>
> Count forward in order to fix it and be more future proof.
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> v2: change the for loop from a backward to a forward one, to ease reading.

fwiw, I prefer your v1, for reasons discussed on a similar patch
fixing the same issue:

https://lists.freedesktop.org/archives/dri-devel/2017-February/133097.html

(although your v1 is a better solution than the original, since we
probably don't want to clk_disable_unprepare() the clk that failed to
enable.)

BR,
-R

> ---
>  drivers/gpu/drm/msm/dsi/dsi_host.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c
> index 1fc07ce24686..e6f56cd8ce08 100644
> --- a/drivers/gpu/drm/msm/dsi/dsi_host.c
> +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c
> @@ -422,7 +422,7 @@ static int dsi_clk_init(struct msm_dsi_host *msm_host)
>  static int dsi_bus_clk_enable(struct msm_dsi_host *msm_host)
>  {
>         const struct msm_dsi_config *cfg = msm_host->cfg_hnd->cfg;
> -       int i, ret;
> +       int i, j, ret;
>
>         DBG("id=%d", msm_host->id);
>
> @@ -437,8 +437,8 @@ static int dsi_bus_clk_enable(struct msm_dsi_host *msm_host)
>
>         return 0;
>  err:
> -       for (; i > 0; i--)
> -               clk_disable_unprepare(msm_host->bus_clks[i]);
> +       for (j = 0; j < i; j++)
> +               clk_disable_unprepare(msm_host->bus_clks[j]);
>
>         return ret;
>  }
> --
> 2.9.3
>