From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: [PATCH] spi: Add a timeout when waiting for transfers Date: Fri, 31 Jan 2014 12:26:17 +0000 Message-ID: <20140131122617.GC22609@sirena.org.uk> References: <1391121536-10937-1-git-send-email-broonie@kernel.org> <20140131114935.GA22609@sirena.org.uk> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="fwblGvOBo7NCOYks" Cc: linux-spi , linaro-kernel-cunTk1MwBs8s++Sfvej+rw@public.gmane.org To: Geert Uytterhoeven Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: --fwblGvOBo7NCOYks Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Jan 31, 2014 at 01:00:31PM +0100, Geert Uytterhoeven wrote: > One other thing: I haven't tried your patch yet, but I'm afraid the 10 ms > may be too small. > E.g. with PIO-based RSPI I don't get more than 2 Mbps, even though > spi-max-frequency = <30000000>, due to the PIO and interrupt overhead. > Hence a 1 MiB read would take ca. 4s, while your timeout would be 300 ms. Hrm, I wouldn't have expected something doing PIO in more than one burst to be letting the transfer run in the background. Though I suppose that might make sense in some situations... I was wondering if that was cutting it a bit fine but more for scheduler reasons, it's what the s3c64xx driver has been using for a while without complaints but may not translate so well with greater exposure. --fwblGvOBo7NCOYks Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAEBAgAGBQJS65ZlAAoJELSic+t+oim9opAP/32ABGnJRpGL+sI/pz0VbM6D S+QV/+0bBEtvkyFCaqXvDwFad956t6IABM35BvdnSmbs8qhRXcSB6o0zbmUoT3c8 DLOAfPPz4PQgf/XscZO7A42KlWC4nAAdBc5qFp4xkkb6npXt0IEnZ61RLr4Btjtu 2AfFC571pkHBYImpCpg2Hpw7QHFAA31ZnXtr0MeYn+znscBNf12FOe0yGyQhib+P qlIp8yEcVJmVebtN0o89fW3xufeoO1XQoPf2ovOahrmLKP1D8kQgIFDGoHb87avb C7fcq8zQ6t/HIPcuOfsKM1MsLuaY6dRgB7QSwqT1ya2ZIF9G0JPT31zbacx8fZhA oaacQ9n0kbIpUca+p30x1c4YGNxvF3uMH0M/pUe1+jw/qNBMO01UDS/DXH7DNcJ8 zPsd9eDw7KEy3OWkQNvwDr8veTpi4ey4DfCJZ7pe+zFNR7v2XeA9r/pTACJRMXRK mmUIc23+5zRlROiT471hKMkcMhiCbeqz7vlZ8j3BRlpcRNEcjLyVv6s3WzyTpauQ Eo+3bfZ33zcdJZ0Ro+tfCTAj/VxmnbBGA0rEQTWDSjBK0g1t0IR52q3OrpgTZOB3 efYiNZhJZWqyrL2dfMbGITT6QPpH9Z7EyTqvMOZtHQF0gTxhiWpY+paNhPZqlrC5 Q6y8TbVWMxKQKTgGrhfx =Bi8t -----END PGP SIGNATURE----- --fwblGvOBo7NCOYks-- -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html