Re: [PATCH 2/4] drm/exynos/mixer: use MXR_GRP_SXY_SY

From: Seung-Woo Kim
Date: Thu May 08 2014 - 00:33:15 EST


Hello Daniel,

On 2014ë 05ì 07ì 23:14, Daniel Kurtz wrote:
> On Wed, May 7, 2014 at 1:14 PM, Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx> wrote:
>> Hi Daniel,
>>
>> On 2014ë 05ì 05ì 00:26, Daniel Kurtz wrote:
>>> Mixer hardware supports offsetting dma from start of source buffer using
>>> the MXR_GRP_SXY register.
>>>
>>> Signed-off-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx>
>>> ---
>>> drivers/gpu/drm/exynos/exynos_mixer.c | 8 +++-----
>>> 1 file changed, 3 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c b/drivers/gpu/drm/exynos/exynos_mixer.c
>>> index 475eb49..40cf39b 100644
>>> --- a/drivers/gpu/drm/exynos/exynos_mixer.c
>>> +++ b/drivers/gpu/drm/exynos/exynos_mixer.c
>>> @@ -529,13 +529,11 @@ static void mixer_graph_buffer(struct mixer_context *ctx, int win)
>>>
>>> dst_x_offset = win_data->crtc_x;
>>> dst_y_offset = win_data->crtc_y;
>>> + src_x_offset = win_data->fb_x;
>>> + src_y_offset = win_data->fb_y;
>>>
>>> /* converting dma address base and source offset */
>>> - dma_addr = win_data->dma_addr
>>> - + (win_data->fb_x * win_data->bpp >> 3)
>>> - + (win_data->fb_y * win_data->fb_width * win_data->bpp >> 3);
>>> - src_x_offset = 0;
>>> - src_y_offset = 0;
>>> + dma_addr = win_data->dma_addr;
>>
>> Basically, you are right and source offset register can be used. But
>> because of limitation of resolution for mixer up to 1920x1080, I
>> considered modified soruce dma address to set one frame buffer, which is
>> bigger than 1920x1080, on to both fimd and hdmi.
>
> Hi Seung-Woo,
>
> I do not see why the maximum MIXER resolution matters for choosing
> between offsetting BASE or using SXY.
>
> Let's say you have one big 1920x1908 framebuffer, with a span of 1920,
> starting at dma_addr (there is no extra padding at the end of the
> line).
> Let's say you wanted the mixer to scan out 1920x1080 pixels starting
> from (0, 800) in the framebuffer, and start drawing them at (0,0) on
> the screen.
>
> What we currently do is:
> BASE = dma_addr + (800 * 1080 * 4)
> SPAN = 1920
> SXY = SX(0) | SY(0)
> WH = W(1920) | H(1080)
> DXY = DX(0) | DY(0)
>
> I am proposing we do:
> BASE = dma_addr
> SPAN = 1920
> SXY = SX(0) | SY(800)
> WH = W(1920) | H(1080)
> DXY = DX(0) | DY(0)
>
> In both cases, the mixer resolution is 1920x1080.

In my test to show each half of big one framebuffer (3840 x 1080) to
FIMD from 0 to 1079 and MIXER from 1080 to 3839 with exynos4210 and
exynos4412, it was failed to show proper hdmi display. Also it is same
for framebuffer (1920 x 2160). AFAIK, it is mainly because mixer dma has
limitation of dma memory size.

In this case, I set register as like:
BASE = dma_addr /* 3840 x 1080 x 4 */
SPAN = 3840
SXY = SX(1920) | SY(0)
WH = W(1920) | H(1080)
DXY = DX(0) | DY(0)
or:
BASE = dma_addr /* 1920 x 2160 x 4 */
SPAN = 1920
SXY = SX(0) | SY(1080)
WH = W(1920) | H(1080)
DXY = DX(0) | DY(0)
but these two setting did not show hdmi display as I expected. So I used
modified dma address.

>
> My motivation for wanting to program an un-modified dma_addr into BASE
> is so we can then just check BASE_S to determine from which buffer the
> mixer is actively being scanned out without worrying about the source
> offset, since the source offset can change for a given framebuffer
> (for example, when doing panning, or if an overlay is used for a HW
> cursor).

Actually, this patch is exactly same with my first implementation, so I
completely understand your motivation. Anyway, I was focus on extended
displays with one buffer, so I wrote modified dma base address.

Thanks and Regards,
- Seung-Woo Kim

>
> Best Regards,
> -Daniel
>
>>
>> Regards,
>> - Seung-Woo Kim
>>
>>>
>>> if (win_data->scan_flags & DRM_MODE_FLAG_INTERLACE)
>>> ctx->interlace = true;
>>>
>>
>> --
>> Seung-Woo Kim
>> Samsung Software R&D Center
>> --
>>
>

--
Seung-Woo Kim
Samsung Software R&D Center
--

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