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SubjectRe: [PATCH] drm/stm: ltdc: add clut mode support
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Hi Peter,

On 11/07/2017 05:34 PM, Peter Rosin wrote:
> On 2017-11-07 16:53, Philippe CORNU wrote:
>> + Peter
>>
>> Hi Peter,
>>
>> CLUT support on STM32 has been removed thanks to your clean up patch
>
> Support is a bit strong for what I thought was a dead function, or
> are you saying that it used to work before my series? Really sorry
> if that is the case!

As I wrote in the previous related thread
(https://lists.freedesktop.org/archives/dri-devel/2017-June/145070.html),
STM32 chipsets supports 8-bit CLUT mode but this driver version does not
support it "yet"...

So, no worry regarding your clean up, I gave you an "acked-by" for that : )

>
> Anyway, the function I removed seemed to indicate that the hardware
> could handle a separate clut for each layer, but your new version
> does not. Why is that?

Yes I confirm the clut support is available for each layer... but I
thought the gamma_lut was only at the crtc level, not at layer level...
Maybe I am wrong.
Moreover, small test applications I used play only with clut at crtc
level...

Anyway, could you please help me to "find" a per-layer clut
implementation because when I read "crtc->state->gamma_lut->data" it
looks like gamma_lut is per crtc, not per plane...? or maybe I have to
add extra properties for that...

Many thanks,
Philippe :-)

>
> Cheers,
> peda
>
>> named "drm: stm: remove dead code and pointless local lut storage"
>> (https://patchwork.freedesktop.org/patch/166898/)
>>
>> This below patch puts back the clut mode support using the new drm gamma
>> api.
>>
>> May I ask you please a short review on this patch?
>>
>> Many thanks,
>> Philippe :-)
>>
>>
>> On 10/26/2017 01:17 PM, Philippe Cornu wrote:
>>> Add the 8-bit clut mode support at crtc level.
>>> Useful for low memory footprint user interfaces but also for
>>> 8-bit old games (including color shifting visual effects).
>>> Tested with fbdev FBIOPUTCMAP & drm DRM_IOCTL_MODE_SETGAMMA
>>> ioctls.
>>>
>>> Signed-off-by: Philippe Cornu <philippe.cornu@st.com>
>>> ---
>>> drivers/gpu/drm/stm/ltdc.c | 30 ++++++++++++++++++++++++++++++
>>> 1 file changed, 30 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
>>> index 7be6710..d5c8a42 100644
>>> --- a/drivers/gpu/drm/stm/ltdc.c
>>> +++ b/drivers/gpu/drm/stm/ltdc.c
>>> @@ -174,6 +174,8 @@
>>>
>>> #define LXCFBLNR_CFBLN GENMASK(10, 0) /* Color Frame Buffer Line Number */
>>>
>>> +#define CLUT_SIZE 256
>>> +
>>> #define CONSTA_MAX 0xFF /* CONSTant Alpha MAX= 1.0 */
>>> #define BF1_PAXCA 0x600 /* Pixel Alpha x Constant Alpha */
>>> #define BF1_CA 0x400 /* Constant Alpha */
>>> @@ -362,6 +364,28 @@ static irqreturn_t ltdc_irq(int irq, void *arg)
>>> * DRM_CRTC
>>> */
>>>
>>> +static void ltdc_crtc_update_clut(struct drm_crtc *crtc)
>>> +{
>>> + struct ltdc_device *ldev = crtc_to_ltdc(crtc);
>>> + struct drm_color_lut *lut;
>>> + u32 val;
>>> + int i;
>>> +
>>> + if (!crtc || !crtc->state)
>>> + return;
>>> +
>>> + if (!crtc->state->color_mgmt_changed || !crtc->state->gamma_lut)
>>> + return;
>>> +
>>> + lut = (struct drm_color_lut *)crtc->state->gamma_lut->data;
>>> +
>>> + for (i = 0; i < CLUT_SIZE; i++, lut++) {
>>> + val = ((lut->red << 8) & 0xff0000) | (lut->green & 0xff00) |
>>> + (lut->blue >> 8) | (i << 24);
>>> + reg_write(ldev->regs, LTDC_L1CLUTWR, val);
>>> + }
>>> +}
>>> +
>>> static void ltdc_crtc_atomic_enable(struct drm_crtc *crtc,
>>> struct drm_crtc_state *old_state)
>>> {
>>> @@ -485,6 +509,8 @@ static void ltdc_crtc_atomic_flush(struct drm_crtc *crtc,
>>>
>>> DRM_DEBUG_ATOMIC("\n");
>>>
>>> + ltdc_crtc_update_clut(crtc);
>>> +
>>> /* Commit shadow registers = update planes at next vblank */
>>> reg_set(ldev->regs, LTDC_SRCR, SRCR_VBR);
>>>
>>> @@ -532,6 +558,7 @@ void ltdc_crtc_disable_vblank(struct drm_device *ddev, unsigned int pipe)
>>> .reset = drm_atomic_helper_crtc_reset,
>>> .atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
>>> .atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
>>> + .gamma_set = drm_atomic_helper_legacy_gamma_set,
>>> };
>>>
>>> /*
>>> @@ -764,6 +791,9 @@ static int ltdc_crtc_init(struct drm_device *ddev, struct drm_crtc *crtc)
>>>
>>> drm_crtc_helper_add(crtc, &ltdc_crtc_helper_funcs);
>>>
>>> + drm_mode_crtc_set_gamma_size(crtc, CLUT_SIZE);
>>> + drm_crtc_enable_color_mgmt(crtc, 0, false, CLUT_SIZE);
>>> +
>>> DRM_DEBUG_DRIVER("CRTC:%d created\n", crtc->base.id);
>>>
>>> /* Add planes. Note : the first layer is used by primary plane */
>
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