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[46.91.226.206]) by smtp.gmail.com with ESMTPSA id j12sm3459171wrb.82.2019.11.18.05.36.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Nov 2019 05:36:15 -0800 (PST) Date: Mon, 18 Nov 2019 14:36:14 +0100 From: Thierry Reding To: Lyude Paul Cc: nouveau@lists.freedesktop.org, Sam Ravnborg , David Airlie , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Jerry Zuo , Sean Paul , Ben Skeggs , Daniel Vetter , David Airlie , Harry Wentland , Juston Li , Laurent Pinchart Subject: Re: [Nouveau] [PATCH 3/3] drm/nouveau/kms/nv50-: Limit MST BPC to 8 Message-ID: <20191118133614.GE2246533@ulmo> References: <20191115210728.3467-1-lyude@redhat.com> <20191115210728.3467-4-lyude@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="BQPnanjtCNWHyqYD" Content-Disposition: inline In-Reply-To: <20191115210728.3467-4-lyude@redhat.com> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --BQPnanjtCNWHyqYD Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Nov 15, 2019 at 04:07:20PM -0500, Lyude Paul wrote: > Noticed this while working on some unrelated CRC stuff. Currently, > userspace has very little support for BPCs higher than 8. While this > doesn't matter for most things, on MST topologies we need to be careful > about ensuring that we do our best to make any given display > configuration fit within the bandwidth restraints of the topology, since > otherwise less people's monitor configurations will work. >=20 > Allowing for BPC settings higher than 8 dramatically increases the > required bandwidth for displays in most configurations, and consequently > makes it a lot less likely that said display configurations will pass > the atomic check. >=20 > In the future we want to fix this correctly by making it so that we > adjust the bpp for each display in a topology to be as high as possible, > while making sure to lower the bpp of each display in the event that we > run out of bandwidth and need to rerun our atomic check. But for now, > follow the behavior that both i915 and amdgpu are sticking to. >=20 > Signed-off-by: Lyude Paul > Fixes: 232c9eec417a ("drm/nouveau: Use atomic VCPI helpers for MST") > Cc: Ben Skeggs > Cc: Daniel Vetter > Cc: David Airlie > Cc: Jerry Zuo > Cc: Harry Wentland > Cc: Juston Li > Cc: Sam Ravnborg > Cc: Sean Paul > Cc: # v5.1+ > --- > drivers/gpu/drm/nouveau/dispnv50/disp.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) Reviewed-by: Thierry Reding --BQPnanjtCNWHyqYD Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAl3Snk4ACgkQ3SOs138+ s6Fi2RAApHjuN6J8fn0XmvXm7CFGwT84x9lf01uGyvRtrhJ7ULOpVbTfcHXk1SL8 Ip8eaNj04DbxO73u9G+2lJkIXmVbyOKxZwCpi9A/UAAoXIspnzZZ6nCWy6124Iqm qpawUa+0q4uz8A/VdALzp60ZilNvX4pZn+mNPbK2V9lrG28vLx0iS6xc+BkMRC4Y rkDmXsdUNiCbVs8OsSK7bBCE3c+g7Z8Hu6z5h5O8yxcG2JDTVLAPindmyZ83Q0qT yqSqqi72QycmqyQ9prZylChv7/z/s7HNp6rMtGG6oCGwguZlwKdIz/Ko01hEKxbd OuX3vhGDe2bhAr/QowPbL4b5ST8ZmeyJ37lldmZAihWEK+BAQHESX/NoaWqDoctc NRIPdzWXvF2VCEy3rLNuUd24ugv+kW9zOYv0ezBoCqq2VZuxSC5Q4rQRFH94oQQ1 OHvPgNRe6P4ZX8gLiZmDdTzQsgJntf/2npXLlJv8muRDuCWqC/d8kGc9xFINqsok pPOBq5OhavcKXVO41RRju8ZqVpy0y+YYqWDynpr97SMTtp11HN3vcrZiB117xllh Fv5rY400AGDpwsaeH/eRm2a+T0Ov2DkegEPFu0IjCuKJ9xMV5RxftSw3HD/7M5hC w+hD4Ixncpohqgaml6M7U/gUIJdafT6N7D8S4LlTcKhvsDFSpVU= =Mrw/ -----END PGP SIGNATURE----- --BQPnanjtCNWHyqYD--