pinctrl: aspeed: Revert "Force to disable the function's signal"

[ Upstream commit 606d4ef ]

This reverts commit cf517fe.

The commit cf517fe ("pinctrl: aspeed: Force to disable the
function's signal") exposed a problem with fetching the regmap for
reading the GFX register.

The Romulus machine the device tree contains a gpio hog for GPIO S7.
With the patch applied:

  Muxing pin 151 for GPIO
  Disabling signal VPOB9 for VPO
  aspeed-g5-pinctrl 1e6e2080.pinctrl: Failed to acquire regmap for IP block 1
  aspeed-g5-pinctrl 1e6e2080.pinctrl: request() failed for pin 151

The code path is aspeed-gpio -> pinmux-g5 -> regmap -> clk, and the
of_clock code returns an error as it doesn't have a valid struct clk_hw
pointer. The regmap call happens because pinmux wants to check the GFX
node (IP block 1) to query bits there.

For reference, before the offending patch:

  Muxing pin 151 for GPIO
  Disabling signal VPOB9 for VPO
  Want SCU8C[0x00000080]=0x1, got 0x0 from 0x00000000
  Disabling signal VPOB9 for VPOOFF1
  Want SCU8C[0x00000080]=0x1, got 0x0 from 0x00000000
  Disabling signal VPOB9 for VPOOFF2
  Want SCU8C[0x00000080]=0x1, got 0x0 from 0x00000000
  Enabling signal GPIOS7 for GPIOS7
  Muxed pin 151 as GPIOS7
  gpio-943 (seq_cont): hogged as output/low

We can't skip the clock check to allow pinmux to proceed, because the
write to disable VPOB9 will try to set a bit in the GFX register space
which will not stick when the IP is in reset. However, we do not want to
enable the IP just so pinmux can do a disable-enable dance for the pin.

For now, revert the offending patch while a correct solution is found.

Fixes: cf517fe ("pinctrl: aspeed: Force to disable the function's signal")
Link: openbmc/linux#218
Signed-off-by: Joel Stanley <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Linus Walleij <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

drivers/pinctrl/aspeed/pinctrl-aspeed.c

@@ -92,10 +92,19 @@ 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);
 
-	return aspeed_sig_expr_set(ctx, expr, false);
+	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;
 }
 
 /**