linux-kernel - Re: [PATCH v9 5/5] drm/sun4i: sun6i_mipi_dsi: Simplify dsi setup timings code

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Date:   Thu, 7 Mar 2019 17:16:44 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Chen-Yu Tsai <wens@...e.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-amarula@...rulasolutions.com,
        Michael Trimarchi <michael@...rulasolutions.com>,
        linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH v9 5/5] drm/sun4i: sun6i_mipi_dsi: Simplify dsi setup
 timings code

On Mon, Mar 4, 2019 at 9:20 PM Maxime Ripard <maxime.ripard@...tlin.com> wrote:
>
> On Sun, Mar 03, 2019 at 11:05:27PM +0530, Jagan Teki wrote:
> > DSI timings are varies between burst/non-burst devices and
> > current driver is handling this support via if, else statements
> > which would difficult to read.
> >
> > Simplify it by using goto to make code more readable.
> >
> > Signed-off-by: Jagan Teki <jagan@...rulasolutions.com>
> > Tested-by: Merlijn Wajer <merlijn@...zup.org>
> > ---
> > Note: This change is created based on previous version burst
> > changes [1] by addressing comment from [2] by Maxime to make
> > code readable.
> >
> > [1] https://patchwork.kernel.org/cover/10813623/
> > [2] https://patchwork.kernel.org/patch/10666607/
> >
> >  drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c | 79 ++++++++++++++------------
> >  1 file changed, 42 insertions(+), 37 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > index 31ec4048804d..898f32319c2d 100644
> > --- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > +++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.c
> > @@ -550,7 +550,8 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
> >  {
> >       struct mipi_dsi_device *device = dsi->device;
> >       unsigned int Bpp = mipi_dsi_pixel_format_to_bpp(device->format) / 8;
> > -     u16 hbp = 0, hfp = 0, hsa = 0, hblk = 0, vblk = 0;
> > +     u16 hbp, hfp, hsa, hblk;
> > +     u16 vblk = 0;
> >       u32 basic_ctl = 0;
> >       size_t bytes;
> >       u8 *buffer;
> > @@ -558,6 +559,7 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
> >       /* Do all timing calculations up front to allocate buffer space */
> >
> >       if (device->mode_flags & MIPI_DSI_MODE_VIDEO_BURST) {
> > +             hbp = hfp = hsa = 0;
>
> This raises a checkpatch warning and isn't necessary
>
> >               hblk = mode->hdisplay * Bpp;
> >               basic_ctl = SUN6I_DSI_BASIC_CTL_VIDEO_BURST |
> >                           SUN6I_DSI_BASIC_CTL_HSA_HSE_DIS |
> > @@ -566,48 +568,51 @@ static void sun6i_dsi_setup_timings(struct sun6i_dsi *dsi,
> >               if (device->lanes == 4)
> >                       basic_ctl |= SUN6I_DSI_BASIC_CTL_TRAIL_FILL |
> >                                    SUN6I_DSI_BASIC_CTL_TRAIL_INV(0xc);
> > -     } else {
> > -             /*
> > -              * A sync period is composed of a blanking packet (4
> > -              * bytes + payload + 2 bytes) and a sync event packet
> > -              * (4 bytes). Its minimal size is therefore 10 bytes
> > -              */
> > +
> > +             goto alloc_buf;
>
> And I'd rather not have a goto in the middle of the code for no
> particular reason.

OK, will try to think for better simplification otherwise will drop it
in next version.