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[92.176.231.205]) by smtp.gmail.com with ESMTPSA id bg17-20020a05600c3c9100b003a04d19dab3sm3251267wmb.3.2022.07.26.06.17.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Jul 2022 06:17:54 -0700 (PDT) Message-ID: Date: Tue, 26 Jul 2022 15:17:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v2 07/10] drm/ofdrm: Add ofdrm for Open Firmware framebuffers Content-Language: en-US To: Thomas Zimmermann , airlied@linux.ie, daniel@ffwll.ch, deller@gmx.de, maxime@cerno.tech, sam@ravnborg.org, msuchanek@suse.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, geert@linux-m68k.org, mark.cave-ayland@ilande.co.uk Cc: linux-fbdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, dri-devel@lists.freedesktop.org References: <20220720142732.32041-1-tzimmermann@suse.de> <20220720142732.32041-8-tzimmermann@suse.de> From: Javier Martinez Canillas In-Reply-To: <20220720142732.32041-8-tzimmermann@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org Hello Thomas, On 7/20/22 16:27, Thomas Zimmermann wrote: > Open Firmware provides basic display output via the 'display' node. > DT platform code already provides a device that represents the node's > framebuffer. Add a DRM driver for the device. The display mode and > color format is pre-initialized by the system's firmware. Runtime > modesetting via DRM is not possible. The display is useful during > early boot stages or as error fallback. > I'm not familiar with OF display but the driver looks good to me. Reviewed-by: Javier Martinez Canillas I just have a few questions below. [...] > +static int ofdrm_primary_plane_helper_atomic_check(struct drm_plane *plane, > + struct drm_atomic_state *new_state) > +{ > + struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(new_state, plane); > + struct drm_crtc_state *new_crtc_state; > + int ret; > + > + if (!new_plane_state->fb) > + return 0; > + > + new_crtc_state = drm_atomic_get_new_crtc_state(new_state, new_plane_state->crtc); > + > + ret = drm_atomic_helper_check_plane_state(new_plane_state, new_crtc_state, > + DRM_PLANE_HELPER_NO_SCALING, > + DRM_PLANE_HELPER_NO_SCALING, > + false, false); > + if (ret) > + return ret; > + > + return 0; > +} This seems to be exactly the same check than used in the simpledrm driver. Maybe could be moved to the fwfb helper library too ? [...] > + > +static void ofdrm_crtc_helper_atomic_disable(struct drm_crtc *crtc, > + struct drm_atomic_state *old_state) > +{ > + /* > + * Always enabled; disabling clears the screen in the > + * primary plane's atomic_disable function. > + */ > +} > + Same comment than for simpledrm, are these no-op helpers really needed ? [...] > +static const struct of_device_id ofdrm_of_match_display[] = { > + { .compatible = "display", }, > + { }, > +}; > +MODULE_DEVICE_TABLE(of, ofdrm_of_match_display); > + I don't see a binding for this in Documentation/devicetree/bindings/display. Do we need one or it's that only required for FDT and not Open Firmware DT ? -- Best regards, Javier Martinez Canillas Linux Engineering Red Hat