From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH v1 2/2] memory: tegra30-emc: Poll EMC-CaR handshake instead of waiting for interrupt Date: Wed, 6 May 2020 18:44:14 +0200 Message-ID: <20200506164414.GB2723987@ulmo> References: <20200319193648.8810-1-digetx@gmail.com> <20200319193648.8810-2-digetx@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="PmA2V3Z32TCmWXqI" Return-path: Content-Disposition: inline In-Reply-To: <20200319193648.8810-2-digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dmitry Osipenko Cc: Jonathan Hunter , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-tegra@vger.kernel.org --PmA2V3Z32TCmWXqI Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Mar 19, 2020 at 10:36:48PM +0300, Dmitry Osipenko wrote: > The memory clock-rate change could be running on a non-boot CPU, while the > boot CPU handles the EMC interrupt. This introduces an unnecessary latency > since boot CPU should handle the interrupt and then notify the sibling CPU > about clock-rate change completion. In some rare cases boot CPU could be > in uninterruptible state for a significant time (like in a case of KASAN + > NFS root), it could get to the point that completion timeouts before boot > CPU gets a chance to handle interrupt. The solution is to get rid of the > completion and replace it with interrupt-status polling. >=20 > Signed-off-by: Dmitry Osipenko > --- > drivers/memory/tegra/tegra30-emc.c | 116 +++++++++++------------------ > 1 file changed, 44 insertions(+), 72 deletions(-) Applied to for-5.8/memory, thanks. Thierry --PmA2V3Z32TCmWXqI Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAl6y6V4ACgkQ3SOs138+ s6FiGxAAuOcRnU09W1bffEluFV80U1jhAPJP4VpwtjyuVwY7NfgJ1Au3jdhKXXsS XCFh+I1aVL9NvC6HEvYdYdrKLxMSlfs/VG19/wU8lqa2enYnJyYeTQBiw/21C/gF pomxj/SYq4yopkWKdEFasndS7RNIqVj2771agc07uOIw+vcQ1gvYmY4ef6xQ/Alr iOk9Juuyxlxt+jCkGbklMgVqGFfF4P9iBstPiI/N8b/PYMppzRKy+jyyApT2G/Vd iqTGb/JHkaJMh9F4OWe/qMzRHISch5SvhVSGM3ueSOZ7T7iSw0kIFo3MCHIjLL46 tM0pKocAwCnCgSRUx944aCJMQUHT8GtuwdUV5IKWKClyMlBpBxnUMhm+gDcXK1ro vOP+nBS8Vr7iqEjVj86ItwJpD2zyrB5biK8FU2MhdpPvtSX4fY7ZHxptWckrP0rs Q9uuoyn7VuweT/rVWOmUlKOEbvzSpqd0+hk6xw1HHLQ77r3SQtxn06iz7qmz64kl SccWii5omSMWkart042lY0oCptG+qfHkg/6iUaP1lJgtNtGyvuemwzf4nY1KIx5b kFdpp5ticnCyJRxBH/o1LfUyeV72zkIbSnM3uI0ML1E48pHbTIim+t++qEwJ/KTJ tsBin2pURNEjo12YgmihIa0LoSV8UwceBxKC2b6zd9iPbYtEa1o= =pb27 -----END PGP SIGNATURE----- --PmA2V3Z32TCmWXqI--