Hi Jyri,
Thank you for the patch.
On Wednesday 08 Feb 2017 16:08:06 Jyri Sarha wrote:
> Let's disable all scaling that requires horizontal decimation with
> higher factor than 4, until we have better estimates of what we can
> and can not do. However, NV12 color format appears to work Ok with
> all decimation factors.
>
> When decimating horizontally by more that 4 the dss is not able to
> fetch the data in burst mode. When this happens it is hard to tell if
> there enough bandwidth. Despite what theory says this appears to be
> true also for 16-bit color formats.
>
> Signed-off-by: Jyri Sarha <jsarha@xxxxxx>
Acked-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
> Chnages since first version:
> - "color_mode_to_bpp(color_mode) > 8" -> "color_mode != OMAP_DSS_COLOR_NV12"
> - commit message and comment updated too
> - improve error print
>
> drivers/gpu/drm/omapdrm/dss/dispc.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/drivers/gpu/drm/omapdrm/dss/dispc.c
> b/drivers/gpu/drm/omapdrm/dss/dispc.c index 5554b72..d956e626 100644
> --- a/drivers/gpu/drm/omapdrm/dss/dispc.c
> +++ b/drivers/gpu/drm/omapdrm/dss/dispc.c
> @@ -2506,6 +2506,25 @@ static int dispc_ovl_calc_scaling_44xx(unsigned long
> pclk, unsigned long lclk, return -EINVAL;
> }
>
> + if (*decim_x > 4 && color_mode != OMAP_DSS_COLOR_NV12) {
> + /*
> + * Let's disable all scaling that requires horizontal
> + * decimation with higher factor than 4, until we have
> + * better estimates of what we can and can not
> + * do. However, NV12 color format appears to work Ok
> + * with all decimation factors.
> + *
> + * When decimating horizontally by more that 4 the dss
> + * is not able to fetch the data in burst mode. When
> + * this happens it is hard to tell if there enough
> + * bandwidth. Despite what theory says this appears to
> + * be true also for 16-bit color formats.
> + */
> + DSSERR("Not enough bandwidth, too much downscaling (x-
decimation factor
> %d > 4)", *decim_x); +
> + return -EINVAL;
> + }
> +
> *core_clk = dispc.feat->calc_core_clk(pclk, in_width, in_height,
> out_width, out_height, mem_to_mem);
> return 0;
--
Regards,
Laurent Pinchart
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