linux-kernel - [PATCH] pinctrl: aspeed: Force to disable the function's signal

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Date:   Thu, 18 Aug 2022 18:18:39 +0800
From:   Billy Tsai <billy_tsai@...eedtech.com>
To:     <andrew@...id.au>, <linus.walleij@...aro.org>, <joel@....id.au>,
        <linux-aspeed@...ts.ozlabs.org>, <openbmc@...ts.ozlabs.org>,
        <linux-gpio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] pinctrl: aspeed: Force to disable the function's signal

When the driver want to disable the signal of the function, it doesn't
need to query the state of the mux function's signal on a pin. The
condition below will miss the disable of the signal:
Ball | Default | P0 Signal | P0 Expression               | Other
-----+---------+-----------+-----------------------------+----------
 E21   GPIOG0    SD2CLK      SCU4B4[16]=1 & SCU450[1]=1    GPIOG0
-----+---------+-----------+-----------------------------+----------
 B22   GPIOG1    SD2CMD      SCU4B4[17]=1 & SCU450[1]=1    GPIOG1
-----+---------+-----------+-----------------------------+----------
Assume the register status like below:
SCU4B4[16] == 1 & SCU4B4[17] == 1 & SCU450[1]==1
After the driver set the Ball E21 to the GPIOG0:
SCU4B4[16] == 0 & SCU4B4[17] == 1 & SCU450[1]==0
When the driver want to set the Ball B22 to the GPIOG1, the condition of
the SD2CMD will be false causing SCU4B4[17] not to be cleared.

Signed-off-by: Billy Tsai <billy_tsai@...eedtech.com>
---
 drivers/pinctrl/aspeed/pinctrl-aspeed.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/drivers/pinctrl/aspeed/pinctrl-aspeed.c b/drivers/pinctrl/aspeed/pinctrl-aspeed.c
index 83d47ff1cea8..a30912a92f05 100644
--- a/drivers/pinctrl/aspeed/pinctrl-aspeed.c
+++ b/drivers/pinctrl/aspeed/pinctrl-aspeed.c
@@ -92,19 +92,10 @@ static int aspeed_sig_expr_enable(struct aspeed_pinmux_data *ctx,
 static int aspeed_sig_expr_disable(struct aspeed_pinmux_data *ctx,
 				   const struct aspeed_sig_expr *expr)
 {
-	int ret;
-
 	pr_debug("Disabling signal %s for %s\n", expr->signal,
 		 expr->function);
 
-	ret = aspeed_sig_expr_eval(ctx, expr, true);
-	if (ret < 0)
-		return ret;
-
-	if (ret)
-		return aspeed_sig_expr_set(ctx, expr, false);
-
-	return 0;
+	return aspeed_sig_expr_set(ctx, expr, false);
 }
 
 /**
-- 
2.25.1