From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752756AbeC1MWl (ORCPT ); Wed, 28 Mar 2018 08:22:41 -0400 Received: from mail-wm0-f50.google.com ([74.125.82.50]:51129 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751207AbeC1MWk (ORCPT ); Wed, 28 Mar 2018 08:22:40 -0400 X-Google-Smtp-Source: AIpwx49eGfFLZ53p4MF9uAzMHS4hi1vODPejd8KIv/HSPeK2UjqirNDgTRSbTILbekl+b2B5Xkb4wQ== Date: Wed, 28 Mar 2018 14:22:36 +0200 From: Daniel Vetter To: Boris Brezillon Cc: Peter Rosin , Egbert Eich , Boris Brezillon , Alexandre Belloni , David Airlie , Nicolas Ferre , Takashi Iwai , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] drm/atmel-hlcdc: add command line option to specify preferred depth Message-ID: <20180328122236.GF14155@phenom.ffwll.local> Mail-Followup-To: Boris Brezillon , Peter Rosin , Egbert Eich , Boris Brezillon , Alexandre Belloni , David Airlie , Nicolas Ferre , Takashi Iwai , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20180326073502.19259-1-peda@axentia.se> <20180328093454.4149fa3b@bbrezillon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180328093454.4149fa3b@bbrezillon> X-Operating-System: Linux phenom 4.15.0-1-amd64 User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 28, 2018 at 09:34:54AM +0200, Boris Brezillon wrote: > Hi Peter, > > On Mon, 26 Mar 2018 09:35:02 +0200 > Peter Rosin wrote: > > > I have an sama5d31-based system with 64MB of memory and a 1920x1080 > > LVDS display wired for 16-bpp. When I enable legacy fbdev support, > > the contiguous memory allocator invariably fails with the order-11 > > allocation for a 1920x1080@24-bpp buffer (~6MB). But this HW can never > > make any good use of RGB888, so that is a wasted attempt anyway that > > would also waste precious memory should it succeed. > > > > Sure, I could rewrite user-space to go directly to KMS etc, and that > > makes the (attempted) order-11 allocation go away, replacing it with > > one order-10 allocation per application restart for a 1920x1080@16-bpp > > buffer (<4MB). But after a few restarts, order-10 allocations start to > > fail as well, which is only to be expected AFAIU. > > > > So, I'd rather not change user-space (which was originally written > > to target a smaller display) so that I at the same time get the > > benefit of an early pre-allocated fbdev frame-buffer that can be > > reused over and over. But to do that I need to tell the driver that > > 16-bpp is the preferred depth. Add a module parameter to do just that. > > > > Signed-off-by: Peter Rosin > > --- > > drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c | 18 +++++++++++++++++- > > 1 file changed, 17 insertions(+), 1 deletion(-) > > > > I found some inspiration regarding naming and implementation here: > > https://patchwork.kernel.org/patch/9848631/ > > > > I have found no feedback on that patch though, which makes me wonder if > > I'm perhaps barking up the wronig tree? > > Hm, isn't that something you can already overload with the video= > parameter? > > video=:[-] > > AFAIR, encodes the color depth, so what is the benefit of adding > this new property to overload the default depth? > > Maybe I'm wrong and the default depth param is actually useful, but in > this case we should probably make it generic since other drivers seems > to need it too, and we might want to attach it to a specific display > engine instance. I think for the drm's fbdev emulation we ignore the bpp ... But yeah probably worth it to wire it up properly. -Daniel > > Thanks, > > Boris > > > > > Cheers, > > Peter > > > > diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c > > index c1ea5c36b006..f0148627c221 100644 > > --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c > > +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c > > @@ -29,6 +29,11 @@ > > > > #define ATMEL_HLCDC_LAYER_IRQS_OFFSET 8 > > > > +static int atmel_hlcdc_preferred_depth __read_mostly; > > + > > +MODULE_PARM_DESC(preferreddepth, "Set preferred bpp"); > > +module_param_named(preferreddepth, atmel_hlcdc_preferred_depth, int, 0400); > > + > > static const struct atmel_hlcdc_layer_desc atmel_hlcdc_at91sam9n12_layers[] = { > > { > > .name = "base", > > @@ -590,6 +595,7 @@ static int atmel_hlcdc_dc_modeset_init(struct drm_device *dev) > > dev->mode_config.min_height = dc->desc->min_height; > > dev->mode_config.max_width = dc->desc->max_width; > > dev->mode_config.max_height = dc->desc->max_height; > > + dev->mode_config.preferred_depth = 24; > > dev->mode_config.funcs = &mode_config_funcs; > > > > return 0; > > @@ -658,7 +664,7 @@ static int atmel_hlcdc_dc_load(struct drm_device *dev) > > > > platform_set_drvdata(pdev, dev); > > > > - drm_fb_cma_fbdev_init(dev, 24, 0); > > + drm_fb_cma_fbdev_init(dev, atmel_hlcdc_preferred_depth, 0); > > > > drm_kms_helper_poll_init(dev); > > > > @@ -756,6 +762,16 @@ static int atmel_hlcdc_dc_drm_probe(struct platform_device *pdev) > > struct drm_device *ddev; > > int ret; > > > > + switch (atmel_hlcdc_preferred_depth) { > > + case 0: /* driver default */ > > + case 8: > > + case 16: > > + case 24: > > + break; > > + default: > > + return -EINVAL; > > + } > > + > > ddev = drm_dev_alloc(&atmel_hlcdc_dc_driver, &pdev->dev); > > if (IS_ERR(ddev)) > > return PTR_ERR(ddev); > > > > -- > Boris Brezillon, Bootlin (formerly Free Electrons) > Embedded Linux and Kernel engineering > https://bootlin.com > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch