ASoC: rsnd: adg: clearly handle clock error / NULL case

Commit Message

Kuninori Morimoto Aug. 20, 2021, 4:08 a.m. UTC

From: Kuninori Morimoto <[e-mail]>

This driver is assuming that all adg->clk[i] is not NULL.
Because of this prerequisites, for_each_rsnd_clk() is possible to work
for all clk without checking NULL. In other words, all adg->clk[i]
should not NULL.

Some SoC might doesn't have clk_a/b/c/i. devm_clk_get() returns error in
such case. This driver calls rsnd_adg_null_clk_get() and use null_clk
instead of NULL in such cases.

But devm_clk_get() might returns NULL even though such clocks exist, but
it doesn't mean error (user deliberately chose to disable the feature).
NULL clk itself is not error from clk point of view, but is error from
this driver point of view because it is not assuming such case.

But current code is using IS_ERR() which doesn't care NULL.
This driver uses IS_ERR_OR_NULL() instead of IS_ERR() for clk check.
And it uses ERR_CAST() to clarify null_clk error.

One concern here is that it unconditionally uses null_clk if clk_a/b/c/i
was error. It is correct if it doesn't exist, but is not correct if it
returns error even though it exist.
It needs to check "clock-names" from DT before calling devm_clk_get() to
handling such case. But let's assume it is overkill so far.

Link: https://lore.kernel.org/r/YMCmhfQUimHCSH/n@mwanda
Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Kuninori Morimoto <[e-mail]>
---
 sound/soc/sh/rcar/adg.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Comments

Mark Brown Aug. 20, 2021, 2:39 p.m. UTC | #1

On 20 Aug 2021 13:08:26 +0900, Kuninori Morimoto wrote:
> From: Kuninori Morimoto <[e-mail]>
> 
> This driver is assuming that all adg->clk[i] is not NULL.
> Because of this prerequisites, for_each_rsnd_clk() is possible to work
> for all clk without checking NULL. In other words, all adg->clk[i]
> should not NULL.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: rsnd: adg: clearly handle clock error / NULL case
      commit: cc64c390b215b404524725a94857d6fb58d9a62a

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

Patch

diff --git a/sound/soc/sh/rcar/adg.c b/sound/soc/sh/rcar/adg.c
index 0ebee1ed06a9..5f1e72edfee0 100644
--- a/sound/soc/sh/rcar/adg.c
+++ b/sound/soc/sh/rcar/adg.c
@@ -391,9 +391,9 @@  static struct clk *rsnd_adg_create_null_clk(struct rsnd_priv *priv,
 	struct clk *clk;
 
 	clk = clk_register_fixed_rate(dev, name, parent, 0, 0);
-	if (IS_ERR(clk)) {
+	if (IS_ERR_OR_NULL(clk)) {
 		dev_err(dev, "create null clk error\n");
-		return NULL;
+		return ERR_CAST(clk);
 	}
 
 	return clk;
@@ -430,9 +430,9 @@  static int rsnd_adg_get_clkin(struct rsnd_priv *priv)
 	for (i = 0; i < CLKMAX; i++) {
 		clk = devm_clk_get(dev, clk_name[i]);
 
-		if (IS_ERR(clk))
+		if (IS_ERR_OR_NULL(clk))
 			clk = rsnd_adg_null_clk_get(priv);
-		if (IS_ERR(clk))
+		if (IS_ERR_OR_NULL(clk))
 			goto err;
 
 		adg->clk[i] = clk;
@@ -582,7 +582,7 @@  static int rsnd_adg_get_clkout(struct rsnd_priv *priv)
 	if (!count) {
 		clk = clk_register_fixed_rate(dev, clkout_name[CLKOUT],
 					      parent_clk_name, 0, req_rate[0]);
-		if (IS_ERR(clk))
+		if (IS_ERR_OR_NULL(clk))
 			goto err;
 
 		adg->clkout[CLKOUT] = clk;
@@ -596,7 +596,7 @@  static int rsnd_adg_get_clkout(struct rsnd_priv *priv)
 			clk = clk_register_fixed_rate(dev, clkout_name[i],
 						      parent_clk_name, 0,
 						      req_rate[0]);
-			if (IS_ERR(clk))
+			if (IS_ERR_OR_NULL(clk))
 				goto err;
 
 			adg->clkout[i] = clk;