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References: <20220109204105.51878-1-colin.i.king@gmail.com> <Ydtoib+OCyaPhrOH@pendragon.ideasonboard.com>
In-Reply-To: <Ydtoib+OCyaPhrOH@pendragon.ideasonboard.com>
From:   Robert Foss <robert.foss@linaro.org>
Date:   Wed, 12 Jan 2022 11:09:06 +0100
Message-ID: <CAG3jFyu3aB0QnQfa-fu6_Zy_=R=9dnVLmW3RBXLv3bD=gUzQEA@mail.gmail.com>
Subject: Re: [PATCH] drm/bridge: adv7533: make array clock_div_by_lanes static const
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     Colin Ian King <colin.i.king@gmail.com>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Sam Ravnborg <sam@ravnborg.org>,
        dri-devel@lists.freedesktop.org, kernel-janitors@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Sun, 9 Jan 2022 at 23:58, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Colin,
>
> Thank you for the patch.
>
> On Sun, Jan 09, 2022 at 08:41:05PM +0000, Colin Ian King wrote:
> > Don't populate the read-only array clock_div_by_lanes on the stack but
> > instead it static const. Also makes the object code a little smaller.
> >
> > Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
> > ---
> >  drivers/gpu/drm/bridge/adv7511/adv7533.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > index eb7579dec40a..ef6270806d1d 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > @@ -29,7 +29,7 @@ static void adv7511_dsi_config_timing_gen(struct adv7511 *adv)
> >       struct mipi_dsi_device *dsi = adv->dsi;
> >       struct drm_display_mode *mode = &adv->curr_mode;
> >       unsigned int hsw, hfp, hbp, vsw, vfp, vbp;
> > -     u8 clock_div_by_lanes[] = { 6, 4, 3 };  /* 2, 3, 4 lanes */
> > +     static const u8 clock_div_by_lanes[] = { 6, 4, 3 };     /* 2, 3, 4 lanes */
>
> It's not mandatory, but I have a tendency to declare static const
> variable first before all mutable variables.
>
> >
> >       hsw = mode->hsync_end - mode->hsync_start;
> >       hfp = mode->hsync_start - mode->hdisplay;
>
> I wonder if
>
>         /* set pixel clock divider mode */
>         regmap_write(adv->regmap_cec, 0x16, (12 / dsi->lanes) << 3);
>
> would be even better, or if it would be too much black magic. Either
> way,
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Applied to drm-misc-next.