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[84.1.217.76]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47f4635aa34sm18097627f8f.15.2026.07.15.15.55.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jul 2026 15:55:36 -0700 (PDT) From: Timur =?UTF-8?B?S3Jpc3TDs2Y=?= To: "Koenig, Christian" , "amd-gfx@lists.freedesktop.org" , "Deucher, Alexander" , Natalie Vock , "Shetaia, Amir" , Marek =?UTF-8?B?T2zFocOhaw==?= , "Limonciello, Mario" , Tvrtko Ursulin , "Kuehling, Felix" , "He, Siwei" , "Yang, Philip" , "Joshi, Mukul" , "Lazar, Lijo" Subject: Re: [PATCH 11/14] drm/amdgpu/ih6.0: Use MMIO ACK for retry CAM on IH 6.0 Date: Thu, 16 Jul 2026 00:55:35 +0200 Message-ID: In-Reply-To: References: <20260701161721.85681-1-timur.kristof@gmail.com> <3014087.Ex9A2HvPv6@timur-max> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Tuesday, July 7, 2026 10:25:09=E2=80=AFAM Central European Summer Time L= azar, Lijo=20 wrote: > On 04-Jul-26 12:20 AM, Timur Krist=C3=B3f wrote: > > On 2026. j=C3=BAlius 3., p=C3=A9ntek 20:11:59 k=C3=B6z=C3=A9p-eur=C3=B3= pai ny=C3=A1ri id=C5=91 Joshi, Mukul > >=20 > > wrote: > >>> I still haven't found any explanation why we use a doorbell for the C= AM > >>> in > >>> the first > >>=20 > >> place? Lijo, Alex, Felix does anybody know that? > >>=20 > >>=20 > >> If I remember correctly, we weren't sure if the IH_RETRY_CAM_ACK regis= ter > >> would be available under > >> virtualization. And we were sure doorbells would > >> work for both bare-metal and virtualization. > >=20 > > Hi Mukul, > >=20 > > Can you clarify that please? > >=20 > > How are retry faults supposed to work under virtualization? Is the > > interrupt processed by the guest or the host? Why is the IH_RETRY_CAM_A= CK > > register not available under virtualization? >=20 > For clarification - CAM entries are separate for PF/VF. ACK register > also has PF/VF copies. However, in general host driver imposes MMIO > register access restrictions to VF, possibly that's the reason. >=20 > Please note that IH_RETRY_INT_CAM_CNTL is PF only. With new versions, > please make sure to add a VF check for programming. Hi Lijo, Can you please clarify what PF and VF means here? I'm not familiar with those abbreviations. Thanks, Timur