linux-kernel - [PATCH v2] ASoC: Revert "ASoC: mediatek: Check for error clk pointer"

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Date:   Mon,  7 Feb 2022 08:09:23 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Matthias Brugger <matthias.bgg@...il.com>
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Guenter Roeck <linux@...ck-us.net>,
        Jiasheng Jiang <jiasheng@...as.ac.cn>,
        Mark Brown <broonie@...nel.org>,
        James Liao <jamesjj.liao@...iatek.com>,
        Kevin Hilman <khilman@...libre.com>,
        Frank Wunderlich <frank-w@...lic-files.de>,
        Daniel Golle <daniel@...rotopia.org>
Subject: [PATCH v2] ASoC: Revert "ASoC: mediatek: Check for error clk pointer"

This reverts commit 9de2b9286a6d ("ASoC: mediatek: Check for error clk
pointer").

With this patch in the tree, Chromebooks running the affected hardware
no longer boot. Bisect points to this patch, and reverting it fixes
the problem.

An analysis of the code with this patch applied shows:

        ret = init_clks(pdev, clk);
        if (ret)
                return ERR_PTR(ret);
...
                for (j = 0; j < MAX_CLKS && data->clk_id[j]; j++) {
                        struct clk *c = clk[data->clk_id[j]];

                        if (IS_ERR(c)) {
                                dev_err(&pdev->dev, "%s: clk unavailable\n",
                                        data->name);
                                return ERR_CAST(c);
                        }

                        scpd->clk[j] = c;
                }

Not all clocks in the clk_names array have to be present. Only the clocks
in the data->clk_id array are actually needed. The code already checks if
the required clocks are available and bails out if not. The assumption that
all clocks have to be present is wrong, and commit 9de2b9286a6d ("ASoC:
mediatek: Check for error clk pointer") needs to be reverted.

Cc: Jiasheng Jiang <jiasheng@...as.ac.cn>
Cc: Mark Brown <broonie@...nel.org>
Cc: James Liao <jamesjj.liao@...iatek.com>
Cc: Kevin Hilman <khilman@...libre.com>
Cc: Matthias Brugger <matthias.bgg@...il.com>
Reported-by: Frank Wunderlich <frank-w@...lic-files.de>
Reported-by: Daniel Golle <daniel@...rotopia.org>
Fixes: 9de2b9286a6d ("ASoC: mediatek: Check for error clk pointer")
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
v2: Updated subject and description, trying to match expected subsystem
    style.
    Replaced two Cc: tags with Reported-by: to give proper credit.

 drivers/soc/mediatek/mtk-scpsys.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c
index 670cc82d17dc..ca75b14931ec 100644
--- a/drivers/soc/mediatek/mtk-scpsys.c
+++ b/drivers/soc/mediatek/mtk-scpsys.c
@@ -411,17 +411,12 @@ static int scpsys_power_off(struct generic_pm_domain *genpd)
 	return ret;
 }
 
-static int init_clks(struct platform_device *pdev, struct clk **clk)
+static void init_clks(struct platform_device *pdev, struct clk **clk)
 {
 	int i;
 
-	for (i = CLK_NONE + 1; i < CLK_MAX; i++) {
+	for (i = CLK_NONE + 1; i < CLK_MAX; i++)
 		clk[i] = devm_clk_get(&pdev->dev, clk_names[i]);
-		if (IS_ERR(clk[i]))
-			return PTR_ERR(clk[i]);
-	}
-
-	return 0;
 }
 
 static struct scp *init_scp(struct platform_device *pdev,
@@ -431,7 +426,7 @@ static struct scp *init_scp(struct platform_device *pdev,
 {
 	struct genpd_onecell_data *pd_data;
 	struct resource *res;
-	int i, j, ret;
+	int i, j;
 	struct scp *scp;
 	struct clk *clk[CLK_MAX];
 
@@ -486,9 +481,7 @@ static struct scp *init_scp(struct platform_device *pdev,
 
 	pd_data->num_domains = num;
 
-	ret = init_clks(pdev, clk);
-	if (ret)
-		return ERR_PTR(ret);
+	init_clks(pdev, clk);
 
 	for (i = 0; i < num; i++) {
 		struct scp_domain *scpd = &scp->domains[i];
-- 
2.35.1