[PATCH] regmap: maple: Don't sync read-only registers

[PATCH] regmap: maple: Don't sync read-only registers

[Takashi Iwai]

regcache_maple_sync() tries to sync all cached values no matter
whether it's writable or not.  OTOH, regache_sync_val() does care the
wrtability and returns -EIO for a read-only register.  This results in
an error message like:
  snd_hda_codec_realtek hdaudioC0D0: Unable to sync register 0x2f0009. -5
and the sync loop is aborted incompletely.

This patch adds the writable register check in the loop for addressing
the bug.

Fixes: f033c26de5a5 ("regmap: Add maple tree based register cache")
Link: https://lore.kernel.org/r/877cs7g6f1.wl-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 drivers/base/regmap/regcache-maple.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/base/regmap/regcache-maple.c b/drivers/base/regmap/regcache-maple.c
index c2e3a0f6c218..d2dad32dd399 100644
--- a/drivers/base/regmap/regcache-maple.c
+++ b/drivers/base/regmap/regcache-maple.c
@@ -203,6 +203,8 @@ static int regcache_maple_sync(struct regmap *map, unsigned int min,
 
 	mas_for_each(&mas, entry, max) {
 		for (r = max(mas.index, lmin); r <= min(mas.last, lmax); r++) {
+			if (!regmap_writeable(map, r))
+				continue;
 			mas_pause(&mas);
 			rcu_read_unlock();
 			ret = regcache_sync_val(map, r, entry[r - mas.index]);
-- 
2.35.3

Re: [PATCH] regmap: maple: Don't sync read-only registers

[Mark Brown]

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On Tue, Jun 13, 2023 at 09:45:11AM +0200, Takashi Iwai wrote:
> regcache_maple_sync() tries to sync all cached values no matter
> whether it's writable or not.  OTOH, regache_sync_val() does care the
> wrtability and returns -EIO for a read-only register.  This results in
> an error message like:
>   snd_hda_codec_realtek hdaudioC0D0: Unable to sync register 0x2f0009. -5
> and the sync loop is aborted incompletely.
> 
> This patch adds the writable register check in the loop for addressing
> the bug.

This should be in _needs_sync().

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Re: [PATCH] regmap: maple: Don't sync read-only registers

[Takashi Iwai]

On Tue, 13 Jun 2023 12:16:37 +0200,
Mark Brown wrote:
> 
> On Tue, Jun 13, 2023 at 09:45:11AM +0200, Takashi Iwai wrote:
> > regcache_maple_sync() tries to sync all cached values no matter
> > whether it's writable or not.  OTOH, regache_sync_val() does care the
> > wrtability and returns -EIO for a read-only register.  This results in
> > an error message like:
> >   snd_hda_codec_realtek hdaudioC0D0: Unable to sync register 0x2f0009. -5
> > and the sync loop is aborted incompletely.
> > 
> > This patch adds the writable register check in the loop for addressing
> > the bug.
> 
> This should be in _needs_sync().

I thought it's a different logic?  regacahe_reg_needs_sync() checks
only whether it's a default value, and other call paths already check
regmap_writeable().

But I can put the check there instead if you still prefer, too.


thanks,

Takashi

Re: [PATCH] regmap: maple: Don't sync read-only registers

[Mark Brown]

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On Tue, Jun 13, 2023 at 12:34:45PM +0200, Takashi Iwai wrote:
> Mark Brown wrote:
> > On Tue, Jun 13, 2023 at 09:45:11AM +0200, Takashi Iwai wrote:

> > This should be in _needs_sync().

> I thought it's a different logic?  regacahe_reg_needs_sync() checks
> only whether it's a default value, and other call paths already check
> regmap_writeable().

Yeah, but it feels like that's the reason we ran into this issue given
that you'd expect _needs_sync() to check this too.

> But I can put the check there instead if you still prefer, too.

It should avoid any similar issues in future.

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Re: [PATCH] regmap: maple: Don't sync read-only registers

[Takashi Iwai]

On Tue, 13 Jun 2023 12:59:27 +0200,
Mark Brown wrote:
> 
> On Tue, Jun 13, 2023 at 12:34:45PM +0200, Takashi Iwai wrote:
> > Mark Brown wrote:
> > > On Tue, Jun 13, 2023 at 09:45:11AM +0200, Takashi Iwai wrote:
> 
> > > This should be in _needs_sync().
> 
> > I thought it's a different logic?  regacahe_reg_needs_sync() checks
> > only whether it's a default value, and other call paths already check
> > regmap_writeable().
> 
> Yeah, but it feels like that's the reason we ran into this issue given
> that you'd expect _needs_sync() to check this too.
> 
> > But I can put the check there instead if you still prefer, too.
> 
> It should avoid any similar issues in future.

OK, then let me cook the v2.


Takashi