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[2003:e4:1f2d:4600:f22f:74ff:fe1f:3a53]) by smtp.gmail.com with ESMTPSA id bn9-20020a170907268900b00a3db46018a4sm3088388ejc.71.2024.02.19.08.31.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Feb 2024 08:31:17 -0800 (PST) Content-Type: multipart/signed; boundary=63829e55cfba98703e2f61921804ec1df7a9f29322c3de52c6af38343b10; micalg=pgp-sha256; protocol="application/pgp-signature" Precedence: bulk X-Mailing-List: linux-tegra@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Date: Mon, 19 Feb 2024 17:31:16 +0100 Message-Id: To: "Mikko Perttunen" Cc: "Mikko Perttunen" , , Subject: Re: [PATCH] gpu: host1x: Skip reset assert on Tegra186 From: "Thierry Reding" X-Mailer: aerc 0.16.0-1-0-g560d6168f0ed-dirty References: <20240214114049.1421463-1-cyndis@kapsi.fi> In-Reply-To: --63829e55cfba98703e2f61921804ec1df7a9f29322c3de52c6af38343b10 Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 On Mon Feb 19, 2024 at 3:18 AM CET, Mikko Perttunen wrote: > On 2/16/24 19:02, Thierry Reding wrote: > > On Wed Feb 14, 2024 at 12:40 PM CET, Mikko Perttunen wrote: > >> From: Mikko Perttunen > >> > >> On Tegra186, other software components may rely on the kernel to > >> keep Host1x operational even during suspend. As such, as a quirk, > >> skip asserting Host1x's reset on Tegra186. > >=20 > > This all sounds a bit vague. What other software components rely on the > > kernel to keep host1x operational during suspend? And why do they do so= ? > > Why is this not a problem elsewhere? > > My assumption is that it's due to a secure world application accessing=20 > NVDEC or display engines during suspend or resume. This happening=20 > without kernel knowledge is a bad thing, but it's hard to change at this= =20 > point. > > The reset line (CAR vs BPMP vs non-accessible reset line), and the=20 > secure application code programming this stuff is slightly different in= =20 > every chip generation, which is where I think the differences happen. *sigh* I guess it is what it is. Please add a bit more background information to the commit message and also a comment for the skip_reset field so that people (including myself) will remember down the road why this exists. 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