Fw: Re: [PATCH 3/3] drm/exynos: enable/disable blend based on pixel format

[Tobias Jakobi]

Hello Joonyoung,

I thought about this some more.


> Gesendet: Freitag, 17. April 2015 um 08:16 Uhr
> Von: "Joonyoung Shim" <jy0922.shim at samsung.com>
> An: "Gustavo Padovan" <gustavo at padovan.org>, 
> linux-samsung-soc at vger.kernel.org
> Cc: dri-devel at lists.freedesktop.org, inki.dae at samsung.com, "Gustavo
> Padovan" <gustavo.padovan at collabora.co.uk>
> Betreff: Re: [PATCH 3/3] drm/exynos: enable/disable blend based on 
> pixel format
> Hi Gustavo,
> 
> On 03/19/2015 11:27 PM, Gustavo Padovan wrote:
>> From: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
>> 
>> Change the switch to use the pixel_format instead of bpp to figure out
>> if we need to enable or disable the layer blending.
>> 
> 
> The default concept is ok about enable or disable of pixel blending
> feature by pixel_format, but it will make to possible blending with
> background layer. I'm not sure whether it's proper or not.
I think one of the reasons why this is currently causing confusion is 
because the background layer is not exposed to userspace. So an idea 
would be to expose BG as a normal DRM plane, with a background_rgb 
propery.

Then we just need to keep track which planes are enabled.

E.g. if just the primary plane is enabled, then we ignore any alpha 
pixelformat (in the sense that we map it to its non-alpha counterpart). 
If another plane, which is located 'underneath', is enabled, then we 
honor the alpha. This could then be the background plane.


With best wishes,
Tobias



> 
> Thanks.
> 
>> Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
>> ---
>> drivers/gpu/drm/exynos/exynos_mixer.c | 29 
>> +++++++++++++++++++++++++----
>> 1 file changed, 25 insertions(+), 4 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c 
>> b/drivers/gpu/drm/exynos/exynos_mixer.c
>> index 7aff88f..0c54098 100644
>> --- a/drivers/gpu/drm/exynos/exynos_mixer.c
>> +++ b/drivers/gpu/drm/exynos/exynos_mixer.c
>> @@ -529,7 +529,7 @@ static void mixer_graph_buffer(struct 
>> mixer_context *ctx, int win)
>> unsigned int x_ratio, y_ratio;
>> unsigned int src_x_offset, src_y_offset, dst_x_offset, dst_y_offset;
>> dma_addr_t dma_addr;
>> - unsigned int fmt;
>> + unsigned int fmt, blend;
>> u32 val;
>> 
>> win_data = &ctx->win_data[win];
>> @@ -539,15 +539,26 @@ static void mixer_graph_buffer(struct 
>> mixer_context *ctx, int win)
>> #define ARGB4444 6
>> #define ARGB8888 7
>> 
>> - switch (win_data->bpp) {
>> - case 16:
>> + switch (win_data->pixel_format) {
>> + case DRM_FORMAT_ARGB4444:
>> fmt = ARGB4444;
>> + blend = 1;
>> break;
>> - case 32:
>> +
>> + case DRM_FORMAT_ARGB8888:
>> + fmt = ARGB8888;
>> + blend = 1;
>> + break;
>> +
>> + case DRM_FORMAT_XRGB8888:
>> fmt = ARGB8888;
>> + blend = 0;
>> break;
>> +
>> default:
>> fmt = ARGB8888;
>> + blend = 0;
>> + break;
>> }
>> 
>> if (win_data->crtc_width != win_data->src_width ||
>> @@ -586,6 +597,16 @@ static void mixer_graph_buffer(struct 
>> mixer_context *ctx, int win)
>> mixer_reg_write(res, MXR_GRAPHIC_SPAN(win),
>> win_data->fb_pitch / (win_data->bpp >> 3));
>> 
>> + if (blend) {
>> + val = MXR_GRP_CFG_BLEND_PRE_MUL;
>> + val |= MXR_GRP_CFG_PIXEL_BLEND_EN;
>> + } else {
>> + val = 0;
>> + }
>> + mixer_reg_writemask(res, MXR_GRAPHIC_CFG(win), val,
>> + MXR_GRP_CFG_BLEND_PRE_MUL
>> + | MXR_GRP_CFG_PIXEL_BLEND_EN);
>> +
>> /* setup display size */
>> if (ctx->mxr_ver == MXR_VER_128_0_0_184 &&
>> win == MIXER_DEFAULT_WIN) {
>> 
> 
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