Re: [PATCH v3 10/24] drm/i2c: tda998x: don't read write-onlyregisters

From: Russell King - ARM Linux
Date: Wed Jan 22 2014 - 16:35:49 EST

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 <moinejf@xxxxxxx>
> ---
> 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

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.

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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".
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