From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Wed, 22 Jan 2014 21:35:35 +0000 Subject: [PATCH v3 10/24] drm/i2c: tda998x: don't read write-only registers In-Reply-To: <20140119195842.24c40e22@armhf> References: <20140119195842.24c40e22@armhf> Message-ID: <20140122213535.GI15937@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sun, Jan 19, 2014 at 07:58:42PM +0100, Jean-Francois Moine wrote: > This patch takes care of the write-only registers of the tda998x. > > The value 'MAT_CONTRL_MAT_SC(1)' in the register MAT_CONTRL has been > set as it is at reset time. > > Signed-off-by: Jean-Francois Moine > --- > v3 > - remarks from Russell King > - don't move the sync polarity setting after the setting of the > register TBG_CNTRL_0 which must be the last setting of the > init sequence This is better, except I find that there's an additional change in this version which wasn't in the original patch 9: > /* must be last register set: */ > - reg_clear(priv, REG_TBG_CNTRL_0, TBG_CNTRL_0_SYNC_ONCE); > + reg_write(priv, REG_TBG_CNTRL_0, 0); Register changes which have a potential effect shouldn't be part of a patch which is really only trying to avoid reading from write only registers. This could be a potential functional change - and it's probably one which Rob Clark should at least be made aware of. As I commented last time, when you're changing register values in an otherwise innocuous patch, you should comment about them in the patch description. -- FTTC broadband for 0.8mile line: 5.8Mbps down 500kbps up. Estimation in database were 13.1 to 19Mbit for a good line, about 7.5+ for a bad. Estimate before purchase was "up to 13.2Mbit".