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([2606:6d00:15:e06b::c41]) by smtp.gmail.com with ESMTPSA id ada2fe7eead31-744d6a3eb8esm8744432137.3.2026.07.13.07.04.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Jul 2026 07:04:04 -0700 (PDT) Message-ID: <5224ab5bffdee0777ecef73a3b96c88e8eed38e8.camel@ndufresne.ca> Subject: Re: [PATCH v7 19/19] gpu: drm: meson: Fix DMA segment size limits and maximize allocation boundaries From: Nicolas Dufresne To: Anand Moon , Neil Armstrong , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Kevin Hilman , Jerome Brunet , Martin Blumenstingl , Mauro Carvalho Chehab , Greg Kroah-Hartman , "open list:DRM DRIVERS FOR AMLOGIC SOCS" , "open list:DRM DRIVERS FOR AMLOGIC SOCS" , "moderated list:ARM/Amlogic Meson SoC support" , open list , "open list:MESON VIDEO DECODER DRIVER FOR AMLOGIC SOCS" , "open list:STAGING SUBSYSTEM" Cc: Doruk Tan Ozturk Date: Mon, 13 Jul 2026 10:04:02 -0400 In-Reply-To: <20260713120840.17427-20-linux.amoon@gmail.com> References: <20260713120840.17427-1-linux.amoon@gmail.com> <20260713120840.17427-20-linux.amoon@gmail.com> Autocrypt: addr=nicolas@ndufresne.ca; prefer-encrypt=mutual; keydata=mDMEaCN2ixYJKwYBBAHaRw8BAQdAM0EHepTful3JOIzcPv6ekHOenE1u0vDG1gdHFrChD /e0J05pY29sYXMgRHVmcmVzbmUgPG5pY29sYXNAbmR1ZnJlc25lLmNhPoicBBMWCgBEAhsDBQsJCA cCAiICBhUKCQgLAgQWAgMBAh4HAheABQkJZfd1FiEE7w1SgRXEw8IaBG8S2UGUUSlgcvQFAmibrjo CGQEACgkQ2UGUUSlgcvQlQwD/RjpU1SZYcKG6pnfnQ8ivgtTkGDRUJ8gP3fK7+XUjRNIA/iXfhXMN abIWxO2oCXKf3TdD7aQ4070KO6zSxIcxgNQFtDFOaWNvbGFzIER1ZnJlc25lIDxuaWNvbGFzLmR1Z nJlc25lQGNvbGxhYm9yYS5jb20+iJkEExYKAEECGwMFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4 AWIQTvDVKBFcTDwhoEbxLZQZRRKWBy9AUCaCyyxgUJCWX3dQAKCRDZQZRRKWBy9ARJAP96pFmLffZ smBUpkyVBfFAf+zq6BJt769R0al3kHvUKdgD9G7KAHuioxD2v6SX7idpIazjzx8b8rfzwTWyOQWHC AAS0LU5pY29sYXMgRHVmcmVzbmUgPG5pY29sYXMuZHVmcmVzbmVAZ21haWwuY29tPoiZBBMWCgBBF iEE7w1SgRXEw8IaBG8S2UGUUSlgcvQFAmibrGYCGwMFCQll93UFCwkIBwICIgIGFQoJCAsCBBYCAw ECHgcCF4AACgkQ2UGUUSlgcvRObgD/YnQjfi4+L8f4fI7p1pPMTwRTcaRdy6aqkKEmKsCArzQBAK8 bRLv9QjuqsE6oQZra/RB4widZPvphs78H0P6NmpIJ User-Agent: Evolution 3.60.2 (3.60.2-1.fc44) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260713_070408_031768_FA34636A X-CRM114-Status: GOOD ( 16.26 ) X-BeenThere: linux-amlogic@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============7871307790387956685==" Sender: "linux-amlogic" Errors-To: linux-amlogic-bounces+linux-amlogic=archiver.kernel.org@lists.infradead.org --===============7871307790387956685== Content-Type: multipart/signed; micalg="pgp-sha512"; protocol="application/pgp-signature"; boundary="=-K7ZLBpNLX5/kwXKFKQKp" --=-K7ZLBpNLX5/kwXKFKQKp Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Le lundi 13 juillet 2026 =C3=A0 17:37 +0530, Anand Moon a =C3=A9crit=C2=A0: > When importing DMABUFs exported by the Amlogic video decoder driver > (meson_vdec) for hardware-accelerated rendering paths, the DMA core > subsystem throws constraint validation warnings. This occurs because the > display controller master device lacks explicit DMA layout configuration, > causing it to fall back to a default 64KB maximum segment size limit. >=20 > Address these architectural constraints during the master bind sequence: >=20 > 1. Initialize and validate a 32-bit coherent DMA allocation window by > =C2=A0=C2=A0 invoking dma_set_mask_and_coherent() with a DMA_BIT_MASK(32)= argument. > 2. Maximize the contiguous scatter-gather allocation segment boundary > =C2=A0=C2=A0 check constraint to UINT_MAX using the dma_set_max_seg_size(= ) helper. >=20 > This guarantees that large video bitstream frame buffers can be imported > and scanned out across sub-driver domains without triggering allocation > warnings or page boundary splits. >=20 > Cc: Nicolas Dufresne > Signed-off-by: Anand Moon Acked-by: Nicolas Dufresne > --- > =C2=A0drivers/gpu/drm/meson/meson_drv.c | 6 ++++++ > =C2=A01 file changed, 6 insertions(+) >=20 > diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/me= son_drv.c > index 49ff9f1f16d32..899e70bca4ce2 100644 > --- a/drivers/gpu/drm/meson/meson_drv.c > +++ b/drivers/gpu/drm/meson/meson_drv.c > @@ -202,6 +202,12 @@ static int meson_drv_bind_master(struct device *dev,= bool has_components) > =C2=A0 if (IS_ERR(drm)) > =C2=A0 return PTR_ERR(drm); > =C2=A0 > + ret =3D dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32)); > + if (ret) > + goto free_drm; > + > + dma_set_max_seg_size(dev, UINT_MAX); > + > =C2=A0 priv =3D devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); > =C2=A0 if (!priv) { > =C2=A0 ret =3D -ENOMEM; --=-K7ZLBpNLX5/kwXKFKQKp Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTvDVKBFcTDwhoEbxLZQZRRKWBy9AUCalTwUgAKCRDZQZRRKWBy 9NNdAQDmsQSLx7lRRr/0dmnss88GGZZ8T5JiUJHYnp57V3Vo9gEA5tSuLIwnYukh D1WBuDEOFQqGktSq40CeUMEDMi1jCgg= =9ZVW -----END PGP SIGNATURE----- --=-K7ZLBpNLX5/kwXKFKQKp-- --===============7871307790387956685== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-amlogic mailing list linux-amlogic@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-amlogic --===============7871307790387956685==--