From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH v1 1/2] memory: tegra20-emc: Poll EMC-CaR handshake instead of waiting for interrupt Date: Wed, 6 May 2020 18:43:59 +0200 Message-ID: <20200506164359.GA2723987@ulmo> References: <20200319193648.8810-1-digetx@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ZGiS0Q5IWpPtfppv" Return-path: Content-Disposition: inline In-Reply-To: <20200319193648.8810-1-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 --ZGiS0Q5IWpPtfppv Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Mar 19, 2020 at 10:36:47PM +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/tegra20-emc.c | 28 +++++++++++----------------- > 1 file changed, 11 insertions(+), 17 deletions(-) Applied to for-5.8/memory, thanks. Thierry --ZGiS0Q5IWpPtfppv Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAl6y6U8ACgkQ3SOs138+ s6ED2g/+J3reqnVaEM79SjqdTgc+vOxhup58zQ1XpVQu0VUIwSeHVxNbmFkC8g8D iyY/AhPcTl/8y4XaF2idwwqfm+uRfp3JNV7/8cQ+UqvTlEaEhVfNeOEaHz7KfWos QfXva6eiLfL+jPI1MSy5I7+mL+Mb/UxT7LbsuKMdLp43kZuwe7i/lz3mbEby7O4z XZQFYsNqaZmzSTC+nhLIucjYZXv+EvdiJDecePeDOWWnGxjb6LbCmvn1cZh4lY0m uO4K3h7F9r+4eGJUiDcBACwG72KV9zYkP3G4uJM9RpxX2PJM0IDDrNRIQtyOgcmw 3CtPXi/WJQtJqnAb3J2uiVakqE9zWvLwFPzIk7JyR9peZrekhv0oZOxsD0c2F3tc ZEEGd6qIitzZra1nduzfw/xiWPFfMXWlTU6SXqVHCgHtEtILF4o1AlYjRi1xXAO5 GbIlSNXTWANpLhH7vzHsOuQpxz8L3KoG8xgAwhhAVCqAEgzKqktdZP148xW6r3nN wHA7blAZEPkmz7Ag6tbM+EbHVf5f6QbLXcpa2Gp3U3AADXUYykpqbBIYdEapMmzQ eEJl6BiLjhWvBcNvsGe5QszLftADT+f6BZOzzCj3MXjUG1sn3AP0EppdCQH5dmSt Amdo4PNmHZj0ObzjAU8zCNsfMJdb/JpY4WOljuIKqSEUHqdLHrE= =jLxc -----END PGP SIGNATURE----- --ZGiS0Q5IWpPtfppv--