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Fri, 02 Oct 2026 08:18:54 +0000 Message-ID: <4041bbf5-d864-43c7-8d3f-e05efd1ce65e@suse.de> Date: Fri, 2 Oct 2026 10:18:53 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: drm/ssd130x: stale pixels when the GPU renders into the framebuffer To: Fabio Piparo , Javier Martinez Canillas Cc: =?UTF-8?Q?Ma=C3=ADra_Canal?= , Melissa Wen , dri-devel@lists.freedesktop.org References: <1f383114-e367-4b67-899b-14a393fece94@suse.de> <20260923160049.1741651-1-holofermes@gmail.com> <4a5917cb-d7d8-489a-85c1-a217b442a355@suse.de> <5cf16665-40a5-4321-a0c8-98af1d0263a0@suse.de> Content-Language: en-US From: Thomas Zimmermann Autocrypt: addr=tzimmermann@suse.de; keydata= xsBNBFs50uABCADEHPidWt974CaxBVbrIBwqcq/WURinJ3+2WlIrKWspiP83vfZKaXhFYsdg XH47fDVbPPj+d6tQrw5lPQCyqjwrCPYnq3WlIBnGPJ4/jreTL6V+qfKRDlGLWFjZcsrPJGE0 BeB5BbqP5erN1qylK9i3gPoQjXGhpBpQYwRrEyQyjuvk+Ev0K1Jc5tVDeJAuau3TGNgah4Yc hdHm3bkPjz9EErV85RwvImQ1dptvx6s7xzwXTgGAsaYZsL8WCwDaTuqFa1d1jjlaxg6+tZsB 9GluwvIhSezPgnEmimZDkGnZRRSFiGP8yjqTjjWuf0bSj5rUnTGiyLyRZRNGcXmu6hjlABEB AAHNJ1Rob21hcyBaaW1tZXJtYW5uIDx0emltbWVybWFubkBzdXNlLmRlPsLAjgQTAQgAOAIb AwULCQgHAgYVCgkICwIEFgIDAQIeAQIXgBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftODH AAoJEGgNwR1TC3ojx1wH/0hKGWugiqDgLNXLRD/4TfHBEKmxIrmfu9Z5t7vwUKfwhFL6hqvo lXPJJKQpQ2z8+X2vZm/slsLn7J1yjrOsoJhKABDi+3QWWSGkaGwRJAdPVVyJMfJRNNNIKwVb U6B1BkX2XDKDGffF4TxlOpSQzdtNI/9gleOoUA8+jy8knnDYzjBNOZqLG2FuTdicBXblz0Mf vg41gd9kCwYXDnD91rJU8tzylXv03E75NCaTxTM+FBXPmsAVYQ4GYhhgFt8S2UWMoaaABLDe 7l5FdnLdDEcbmd8uLU2CaG4W2cLrUaI4jz2XbkcPQkqTQ3EB67hYkjiEE6Zy3ggOitiQGcqp j//OwE0EWznS4AEIAMYmP4M/V+T5RY5at/g7rUdNsLhWv1APYrh9RQefODYHrNRHUE9eosYb T6XMryR9hT8XlGOYRwKWwiQBoWSDiTMo/Xi29jUnn4BXfI2px2DTXwc22LKtLAgTRjP+qbU6 3Y0xnQN29UGDbYgyyK51DW3H0If2a3JNsheAAK+Xc9baj0LGIc8T9uiEWHBnCH+RdhgATnWW GKdDegUR5BkDfDg5O/FISymJBHx2Dyoklv5g4BzkgqTqwmaYzsl8UxZKvbaxq0zbehDda8lv hFXodNFMAgTLJlLuDYOGLK2AwbrS3Sp0AEbkpdJBb44qVlGm5bApZouHeJ/+n+7r12+lqdsA EQEAAcLAdgQYAQgAIAIbDBYhBHIX+6yM6c9jRKFo5WgNwR1TC3ojBQJftOH6AAoJEGgNwR1T C3ojVSkIALpAPkIJPQoURPb1VWjh34l0HlglmYHvZszJWTXYwavHR8+k6Baa6H7ufXNQtThR yIxJrQLW6rV5lm7TjhffEhxVCn37+cg0zZ3j7zIsSS0rx/aMwi6VhFJA5hfn3T0TtrijKP4A SAQO9xD1Zk9/61JWk8OysuIh7MXkl0fxbRKWE93XeQBhIJHQfnc+YBLprdnxR446Sh8Wn/2D Ya8cavuWf2zrB6cZurs048xe0UbSW5AOSo4V9M0jzYI4nZqTmPxYyXbm30Kvmz0rYVRaitYJ 4kyYYMhuULvrJDMjZRvaNe52tkKAvMevcGdt38H4KSVXAylqyQOW5zvPc4/sq9c= In-Reply-To: Content-Type: text/plain; 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DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Action: no action X-Rspamd-Queue-Id: EC7231FE4A X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi Am 30.09.26 um 20:45 schrieb Fabio Piparo: > Hi all, > > On Wed, Sep 30, 2026 at 2:48 AM Thomas Zimmermann wrote: >> Those buffers should have been allocated on the v3d side. > Ah! Now I think I see what's happening. Some context on where I'm > coming from, since I think I explained it badly. > > My program opens the panel's card and lets Mesa handle the buffers. > > fd = open("/dev/dri/card2", O_RDWR); /* ssd130x */ > gbm = gbm_create_device(fd); > surf = gbm_surface_create(gbm, 128, 32, GBM_FORMAT_XRGB8888, > GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING); > bo = gbm_surface_lock_front_buffer(surf); > > On a Pi 4/5 Mesa hands me dumb buffers from ssd130x with v3d drawing > into them. On a Pi 0-3 it goes the other way, the GPU makes the > buffers and ssd130x imports them, and that works fine. > > Reading this thread convinced me that what I was doing was wrong for > my use case, and that my program should own the buffers itself. So now > it does the producer-consumer thing: > > gpu = gbm_create_device(open("/dev/dri/renderD128", O_RDWR)); /* v3d */ > bo = gbm_bo_create(gpu, 128, 32, GBM_FORMAT_XRGB8888, > GBM_BO_USE_RENDERING | GBM_BO_USE_LINEAR); > drmPrimeFDToHandle(fd, gbm_bo_get_fd(bo), &handle); > /* AddFB2 with that handle, draw into bo through an EGLImage, page flip */ > > That's clean on a stock kernel and stock Mesa. Great to hear that it works now Best regards Thomas > > By the way, I found one other report that looks like the same thing, > from March 2024: https://github.com/notro/gud/issues/22 > > Thanks, > Fabio/ -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com GF: Stefan Gaiser, Jochen Jaser, Abhinav Puri, (HRB 36809, AG Nürnberg)