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Thu, 03 Sep 2026 15:39:12 +0200 Message-ID: Date: Thu, 3 Sep 2026 10:39:05 -0300 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/4] drm/vc4: Reset the V3D block through the reset controller To: Maxime Ripard , Dave Stevenson , Raspberry Pi Kernel Maintenance , Stefan Wahren , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Florian Fainelli , Ray Jui , Scott Branden , Broadcom internal kernel review list Cc: kernel-dev@igalia.com, dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org References: <20260816-vc4-reset-control-v1-0-896444373716@igalia.com> From: =?UTF-8?Q?Ma=C3=ADra_Canal?= Content-Language: en-US Autocrypt: addr=mcanal@igalia.com; keydata= xsBNBGcCwywBCADgTji02Sv9zjHo26LXKdCaumcSWglfnJ93rwOCNkHfPIBll85LL9G0J7H8 /PmEL9y0LPo9/B3fhIpbD8VhSy9Sqz8qVl1oeqSe/rh3M+GceZbFUPpMSk5pNY9wr5raZ63d gJc1cs8XBhuj1EzeE8qbP6JAmsL+NMEmtkkNPfjhX14yqzHDVSqmAFEsh4Vmw6oaTMXvwQ40 SkFjtl3sr20y07cJMDe++tFet2fsfKqQNxwiGBZJsjEMO2T+mW7DuV2pKHr9aifWjABY5EPw G7qbrh+hXgfT+njAVg5+BcLz7w9Ju/7iwDMiIY1hx64Ogrpwykj9bXav35GKobicCAwHABEB AAHNIE1hw61yYSBDYW5hbCA8bWNhbmFsQGlnYWxpYS5jb20+wsCRBBMBCAA7FiEE+ORdfQEW dwcppnfRP/MOinaI+qoFAmcCwywCGwMFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgkQ P/MOinaI+qoUBQgAqz2gzUP7K3EBI24+a5FwFlruQGtim85GAJZXToBtzsfGLLVUSCL3aF/5 O335Bh6ViSBgxmowIwVJlS/e+L95CkTGzIIMHgyUZfNefR2L3aZA6cgc9z8cfow62Wu8eXnq GM/+WWvrFQb/dBKKuohfBlpThqDWXxhozazCcJYYHradIuOM8zyMtCLDYwPW7Vqmewa+w994 7Lo4CgOhUXVI2jJSBq3sgHEPxiUBOGxvOt1YBg7H9C37BeZYZxFmU8vh7fbOsvhx7Aqu5xV7 FG+1ZMfDkv+PixCuGtR5yPPaqU2XdjDC/9mlRWWQTPzg74RLEw5sz/tIHQPPm6ROCACFls7A TQRnAsMsAQgAxTU8dnqzK6vgODTCW2A6SAzcvKztxae4YjRwN1SuGhJR2isJgQHoOH6oCItW Xc1CGAWnci6doh1DJvbbB7uvkQlbeNxeIz0OzHSiB+pb1ssuT31Hz6QZFbX4q+crregPIhr+ 0xeDi6Mtu+paYprI7USGFFjDUvJUf36kK0yuF2XUOBlF0beCQ7Jhc+UoI9Akmvl4sHUrZJzX LMeajARnSBXTcig6h6/NFVkr1mi1uuZfIRNCkxCE8QRYebZLSWxBVr3h7dtOUkq2CzL2kRCK T2rKkmYrvBJTqSvfK3Ba7QrDg3szEe+fENpL3gHtH6h/XQF92EOulm5S5o0I+ceREwARAQAB wsB2BBgBCAAgFiEE+ORdfQEWdwcppnfRP/MOinaI+qoFAmcCwywCGwwACgkQP/MOinaI+qpI zQf+NAcNDBXWHGA3lgvYvOU31+ik9bb30xZ7IqK9MIi6TpZqL7cxNwZ+FAK2GbUWhy+/gPkX it2gCAJsjo/QEKJi7Zh8IgHN+jfim942QZOkU+p/YEcvqBvXa0zqW0sYfyAxkrf/OZfTnNNE Tr+uBKNaQGO2vkn5AX5l8zMl9LCH3/Ieaboni35qEhoD/aM0Kpf93PhCvJGbD4n1DnRhrxm1 uEdQ6HUjWghEjC+Jh9xUvJco2tUTepw4OwuPxOvtuPTUa1kgixYyG1Jck/67reJzMigeuYFt raV3P8t/6cmtawVjurhnCDuURyhUrjpRhgFp+lW8OGr6pepHol/WFIOQEg== In-Reply-To: <20260816-vc4-reset-control-v1-0-896444373716@igalia.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260903_064001_869841_B0F529C1 X-CRM114-Status: GOOD ( 22.06 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, Florian, Stefan and other Broadcom engineers, any thoughts about this series? Best regards, - Maíra On 16/08/26 11:05, Maíra Canal wrote: > vc4_reset() recovers a hung GPU by dropping the runtime PM usage count to > zero so that the V3D power domain goes down, and then taking it again. > Forcing the count to zero only works if the driver knows exactly how many > references it holds, which is why vc4 unconventionaly wraps every > pm_runtime_get_sync() call in a private refcount and mutex, making the > code cumbersome. > > The BCM2835 PM block has exposed a reset line for the V3D block since > commit 670c672608a1 ("soc: bcm: bcm2835-pm: Add support for power domains > under a new binding."), added for exactly this reason, but vc4 never > picked it up. This series switches vc4 over to it and drops the private > refcount, leaving vc4_v3d_pm_get/put() as plain runtime PM wrappers. > > The reset line is optional, so device trees that do not describe one keep > working: they get the driver-side recovery in vc4_irq_reset() while the > hardware is left untouched. Of the two in-tree platforms, > > 1. BCM2835 gains the property in PATCH 4. > 2. Cygnus has no V3D power domain to begin with, so the power-cycle > only ever gated its clock there. > > PATCH 1 is an independent cleanup. "brcm,vc4-v3d" was never documented > and was never used by any in-tree device tree, so it is a candidate for > removal on its own. It can be dropped from the series if it turns out > to be contentious. > > This series was tested on the Raspberry Pi 3B and 3B+. > > Best regards, > - Maíra > > --- > Maíra Canal (4): > drm/vc4: Drop the undocumented brcm,vc4-v3d compatible > dt-bindings: display: bcm2835-v3d: Add an optional reset line > drm/vc4: Use the reset controller to recover from a GPU hang > ARM: dts: bcm2835: Add the V3D reset line > > .../bindings/display/brcm,bcm2835-v3d.yaml | 3 ++ > arch/arm/boot/dts/broadcom/bcm2835-common.dtsi | 1 + > drivers/gpu/drm/vc4/vc4_drv.c | 1 - > drivers/gpu/drm/vc4/vc4_drv.h | 13 ++++--- > drivers/gpu/drm/vc4/vc4_gem.c | 40 +++++++++++++--------- > drivers/gpu/drm/vc4/vc4_irq.c | 7 ++-- > drivers/gpu/drm/vc4/vc4_v3d.c | 37 +++++++------------- > 7 files changed, 51 insertions(+), 51 deletions(-) > --- > base-commit: 09b47186a4164f3aaa3591313f80794443117342 > change-id: 20260812-vc4-reset-control-cddf3eb8a9e9 >