linux-kernel - Re: [PATCH v5 1/2] drm: tilcdc: implement palette loading for rev1

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Date:   Wed, 16 Nov 2016 16:40:32 +0200
From:   Jyri Sarha <jsarha@...com>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>
CC:     Tomi Valkeinen <tomi.valkeinen@...com>,
        David Airlie <airlied@...ux.ie>,
        Kevin Hilman <khilman@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        Sekhar Nori <nsekhar@...com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-drm <dri-devel@...ts.freedesktop.org>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v5 1/2] drm: tilcdc: implement palette loading for rev1

On 11/16/16 13:34, Bartosz Golaszewski wrote:
> 2016-10-31 17:05 GMT+01:00 Jyri Sarha <jsarha@...com>:
>> On 10/31/16 16:19, Bartosz Golaszewski wrote:
>>> Revision 1 of the IP doesn't work if we don't load the palette (even
>>> if it's not used, which is the case for the RGB565 format).
>>>
>>> Add a function called from tilcdc_crtc_enable() which performs all
>>> required actions if we're dealing with a rev1 chip.
>>>
>>
>> There is only one thing I do not like about this patch. The palette
>> loading is done so late that the frame buffer address are already placed
>> into DMA base and ceiling registers, and we need to read them from the
>> registers and restore them back after the palette loading.
>>
>> Could you try if the palette loading function works without trouble when
>> called from tilcdc_pm_resume() before drm_atomic_helper_resume() call?
>> If it does it would be cleaner in the sense that you could get rid off
>> the old dma address restore code. You could reinit the completion always
>> there right before the palette loading.
>>
>> If you can not get the above suggestion to work, then I can take this
>> patch.
>>
> 
> Hi Jyri,
> 
> the problem is that tilcdc_pm_resume() is not called when tilcdc is
> initialized. We would have to have two calls in different places for
> that to work.
> 

Yep, I know now. I worked on the issue while you were on vacation.
Please review my latest patch series (including this patch) and more
importantly test if the palette loading still works on rev 1 LCDC.

>>> +static void tilcdc_crtc_load_palette(struct drm_crtc *crtc)
>>> +{
>>> +     u32 dma_fb_base, dma_fb_ceiling, raster_ctl;
>>> +     struct tilcdc_crtc *tilcdc_crtc;
>>> +     struct drm_device *dev;
>>> +     u16 *first_entry;
>>> +
>>> +     dev = crtc->dev;
>>> +     tilcdc_crtc = to_tilcdc_crtc(crtc);
>>> +     first_entry = tilcdc_crtc->palette_base;
>>> +
>>> +     *first_entry = TILCDC_REV1_PALETTE_FIRST_ENTRY;
>>> +
>>> +     dma_fb_base = tilcdc_read(dev, LCDC_DMA_FB_BASE_ADDR_0_REG);
>>> +     dma_fb_ceiling = tilcdc_read(dev, LCDC_DMA_FB_CEILING_ADDR_0_REG);
>>> +     raster_ctl = tilcdc_read(dev, LCDC_RASTER_CTRL_REG);
>>> +
>>> +     /* Tell the LCDC where the palette is located. */
>>> +     tilcdc_write(dev, LCDC_DMA_FB_BASE_ADDR_0_REG,
>>> +                  tilcdc_crtc->palette_dma_handle);
>>> +     tilcdc_write(dev, LCDC_DMA_FB_CEILING_ADDR_0_REG,
>>> +                  (u32)tilcdc_crtc->palette_dma_handle
>>
>> Just a nit pick, but I would put the plus sign to the end of the line
>> above instead of the beginning of the line bellow. However,
>> check_patch.pl does not complain about this so I guess I can accept it too.
>>
>>> +                             + TILCDC_REV1_PALETTE_SIZE - 1);
>>> +
> 
> I'll fix that in v6.
> 
> Thanks,
> Bartosz Golaszewski
>