From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: [PATCH] ASoC: da732x: Mark DC offset control registers volatile Date: Tue, 25 Feb 2014 10:21:38 +0900 Message-ID: <20140225012138.GK25940@sirena.org.uk> References: <1393210853-32246-1-git-send-email-broonie@kernel.org> <2E89032DDAA8B9408CB92943514A03376BAD3FC8@SW-EX-MBX01.diasemi.com> <20140224124230.GF25940@sirena.org.uk> <2E89032DDAA8B9408CB92943514A03376BAD405D@SW-EX-MBX01.diasemi.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="teB4kYKCoFg+dcUh" Return-path: Content-Disposition: inline In-Reply-To: <2E89032DDAA8B9408CB92943514A03376BAD405D@SW-EX-MBX01.diasemi.com> Sender: stable-owner@vger.kernel.org To: "Opensource [Adam Thomson]" Cc: Liam Girdwood , "alsa-devel@alsa-project.org" , "linaro-kernel@lists.linaro.org" , "stable@vger.kernel.org" List-Id: alsa-devel@alsa-project.org --teB4kYKCoFg+dcUh Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Feb 24, 2014 at 01:57:53PM +0000, Opensource [Adam Thomson] wrote: > anyway. I'd be tempted to keep it simple and just make those registers volatile, > then you know it will work as expected, at least for the time being until a That breaks suspend and resume without further work - for suspend and resume we generally rely on restoring the register cache to restore the current settings but if a register is volatile it won't be cached so will go back to the hardware defaults after suspend. The ability to avoid I2C traffic is partly just a nice side effect (though it was needed on devices that don't have readback), the main thing these days is that controls get efficient suspend and resume handling for free. Refactoring the offset correction to happen once on startup would solve the issue since the cache could just be bypassed, though you are likely to find that there is some run to run variation for the callibration due to effects like thermal variation and simple measurement errors. Still, the effects are typically very small. --teB4kYKCoFg+dcUh Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAEBAgAGBQJTC/AfAAoJELSic+t+oim9GTUP/idaL0Ku0s1Nxe6uExqBNqJl aRom7QFTJbrn0L0ZDDFf8n63/bdWaRvHM95lft0VJWiayQD8FfOYGcP1vbqWOJX7 GVVKWTmtg8PrvnDP5Qd982mJ+wKPts2hhECLu7BvWCvuwOpbGR4tCdrXXRmwmPOU 01VvSa/pclwQ8P1EQVZTZptnorIDqVMUJyVu91L9NQxVlONXRUMUHk/yBqfDSlXr uWUWWu+jCcf9lLDa5IMcLUabi9IuCfyQFoOuDie4Og3/9T5OQF+qXGZcZSjoO+UP WhgLpLBMwXMky1KfKLTqNiiL2S5+W8/mz5sXw/Y7lfs7BAlMaee2cuoLqjGtIoa4 hHFVI0lfJXWKtOlgeA06gmVskrJtp0N87JB5WZZ/H99QoZVCUHSIdp0KUUHgRCf8 XuqmNDv2pDHMK0m1A2cQ0k+JHhajCKa/Nxu2KASlDq6UfxytDNksMO88H5Jeqp+A 9MzBPETH7dpQC1ikOPV6dd3RCLQKCIWZj0lusXRSE1k2jYPaz+2TauRmBenHv5Cy U4e+/IWXqsqlUXz0I1mFQe2LcXGUKHFZlNiA/Ars2MUBEnO/NrZOAcmJn+5mYGHV e8HuuJWFA7QDLkEoTOdhpChWX4DfaXxs5bPnKKiWhc2mqWCtg7CmQsXPBcgGU5mB 8AGSptXB6vJPrk0D9m6B =Wj+y -----END PGP SIGNATURE----- --teB4kYKCoFg+dcUh--