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Date: Fri, 24 Nov 2017 13:54:05 +0000 From: Philippe CORNU <philippe.cornu@...com> To: Peter Rosin <peda@...ntia.se>, Yannick FERTRE <yannick.fertre@...com>, Benjamin Gaignard <benjamin.gaignard@...aro.org>, Vincent ABRIOU <vincent.abriou@...com>, David Airlie <airlied@...ux.ie>, "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> CC: Fabien DESSENNE <fabien.dessenne@...com>, Mickael REULIER <mickael.reulier@...com>, Gabriel FERNANDEZ <gabriel.fernandez@...com>, Ludovic BARRE <ludovic.barre@...com>, Alexandre TORGUE <alexandre.torgue@...com>, Maxime Coquelin <mcoquelin.stm32@...il.com> Subject: Re: [PATCH] drm/stm: ltdc: add clut mode support Hi Peter, On 11/13/2017 11:40 AM, Philippe CORNU wrote: > Hi Peter, > > On 11/12/2017 01:31 PM, Peter Rosin wrote: >> On 2017-11-10 17:12, Philippe CORNU wrote: >>> 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 : ) >> >> Ok, good. Thanks for clearing that up! >> >>>> >>>> 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... >> >> I wasn't clear enough. Yes, there is to my knowledge only one clut, >> not one per plane. What I noticed was that the function I removed >> seemed to touch clut registers for multiple layers, but your new >> function appears to only touch registers for one layer. So, I >> wondered if the "one and only" clut needed to be copied to the >> registers for the other layers, or if the old dead code was simply >> confused. Clearer? >> > > The old code was a generic helper function (ie. for all layers) but used > only for the 1st layer. So, we could say that "old dead code was simply > confused" :-) > > When I put back the clut support in this patch, I decided to update only > the 1st layer (because there is no API for handling it on other layers). > I also decided to not re-use the former generic helper function as the > update loop is pretty small. > > This patch offers the clut mode feature for fbdev (only one plane in > fbdev) and for drm (single plane for many use cases, 2nd plane being > used mostly for video...) > > If tomorrow the API offers clut support per plane, the update loop will > be moved to the plane update function, means the generic helper function > will not be require anymore too. From the explanations above, do you think the patch is "acceptable" or should I change it somehow? What is your opinion? Many thanks, Philippe :-) > > Many thanks > Philippe :) > >> Cheers. >> Peter >>
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