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Mon, 14 Sep 2026 03:23:46 -0700 (PDT) Received: from localhost ([2c0f:3d00:6be:8900:ce5e:9212:ea4b:f30]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c2966021c63sm404118766b.13.2026.09.14.03.23.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Sep 2026 03:23:45 -0700 (PDT) Date: Mon, 14 Sep 2026 13:23:42 +0300 From: Dan Carpenter To: Leo Chen Cc: amd-gfx@lists.freedesktop.org, "SHANMUGAM, SRINIVASAN" Subject: Re: [bug report] drm/amd/display: Register DCN as a PMFW DF C-state client on DCN42 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Mailman-Approved-At: Mon, 14 Sep 2026 12:47:06 +0000 X-BeenThere: amd-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces@lists.freedesktop.org Sender: "amd-gfx" On Mon, Sep 14, 2026 at 01:21:43PM +0300, Dan Carpenter wrote: > Hello Leo Chen, > > Commit 53845307d52e ("drm/amd/display: Register DCN as a PMFW DF > C-state client on DCN42") from Jul 9, 2026, leads to the following > Smatch complaint: > > drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn42/dcn42_hwseq.c:686 dcn42_prepare_bandwidth() > warn: variable dereferenced before check 'dc->clk_mgr' (see line 681) > > drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn42/dcn42_hwseq.c > 680 > 681 dcn401_prepare_bandwidth(dc, context); > ^^ > dc->clk_mgr is dereferenced here. > > 682 > 683 /* valid C-state watermarks have now been committed to HW, so it > 684 * is safe to vote "allow" to PMFW. > 685 */ > 686 if (dc->clk_mgr && dc->clk_mgr->funcs && dc->clk_mgr->funcs->notify_cstate_disable) > ^^^^^^^^^^^ > so this check is too late. > Actually, dc->clk_mgr->funcs is dereferenced as well. regards, dan carpenter