Re: [PATCH v6 1/5] drm/vc4: Move the DSI clock divider workaround closer to the clock call.

Boris Brezillon
2017-10-11T11:54:17Z

On Tue, 15 Aug 2017 16:47:18 -0700
Eric Anholt <eric@anholt.net> wrote:

> We want the adjusted_mode->clock to be the actual clock we're
> expecting to program, so that consumers see the right values for clock
> and vrefresh.
>
> Signed-off-by: Eric Anholt <eric@anholt.net>

Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>

> ---
> drivers/gpu/drm/vc4/vc4_dsi.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
> index d1e0dc908048..eb787eed8abe 100644
> --- a/drivers/gpu/drm/vc4/vc4_dsi.c
> +++ b/drivers/gpu/drm/vc4/vc4_dsi.c
> @@ -859,11 +859,7 @@ static bool vc4_dsi_encoder_mode_fixup(struct drm_encoder *encoder,
> pll_clock = parent_rate / divider;
> pixel_clock_hz = pll_clock / dsi->divider;
>
> - /* Round up the clk_set_rate() request slightly, since
> - * PLLD_DSI1 is an integer divider and its rate selection will
> - * never round up.
> - */
> - adjusted_mode->clock = pixel_clock_hz / 1000 + 1;
> + adjusted_mode->clock = pixel_clock_hz / 1000;
>
> /* Given the new pixel clock, adjust HFP to keep vrefresh the same. */
> adjusted_mode->htotal = pixel_clock_hz / (mode->vrefresh * mode->vtotal);
> @@ -900,7 +896,11 @@ static void vc4_dsi_encoder_enable(struct drm_encoder *encoder)
> vc4_dsi_dump_regs(dsi);
> }
>
> - phy_clock = pixel_clock_hz * dsi->divider;
> + /* Round up the clk_set_rate() request slightly, since
> + * PLLD_DSI1 is an integer divider and its rate selection will
> + * never round up.
> + */
> + phy_clock = (pixel_clock_hz + 1000) * dsi->divider;
> ret = clk_set_rate(dsi->pll_phy_clock, phy_clock);
> if (ret) {
> dev_err(&dsi->pdev->dev,