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FAILED: patch "[PATCH] spi: Assume GPIO CS active high in ACPI case" failed to apply to 5.12-stable tree

PATCH [email protected] 1 participant 1 message May 30, 2021

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The patch below does not apply to the 5.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6b69546912a57ff8c31061f98e56383cc0beffd3 Mon Sep 17 00:00:00 2001
From: Andy Shevchenko <[email protected]>
Date: Tue, 11 May 2021 17:09:12 +0300
Subject: [PATCH] spi: Assume GPIO CS active high in ACPI case

Currently GPIO CS handling, when descriptors are in use, doesn't take into consideration that in ACPI case the default polarity is Active High and can't be altered. Instead we have to use the per-chip definition provided by SPISerialBus() resource.

Fixes 766c6b63aa04 ("spi: fix client driver breakages when using GPIO descriptors")
Cc Liguang Zhang <[email protected]>
Cc Jay Fang <[email protected]>
Cc Sven Van Asbroeck <[email protected]>
Signed-off-by Andy Shevchenko <[email protected]>
Tested-by Xin Hao <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Mark Brown <[email protected]>
drivers/spi/spi.c +18 -4
index a565e7d6bf3b..98048af04abf 100644
@@ -820,15 +820,29 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
 
 	if (spi->cs_gpiod || gpio_is_valid(spi->cs_gpio)) {
 		if (!(spi->mode & SPI_NO_CS)) {
-			if (spi->cs_gpiod)
-				/* polarity handled by gpiolib */
-				gpiod_set_value_cansleep(spi->cs_gpiod, activate);
-			else
+			if (spi->cs_gpiod) {
+				/*
+				 * Historically ACPI has no means of the GPIO polarity and
+				 * thus the SPISerialBus() resource defines it on the per-chip
+				 * basis. In order to avoid a chain of negations, the GPIO
+				 * polarity is considered being Active High. Even for the cases
+				 * when _DSD() is involved (in the updated versions of ACPI)
+				 * the GPIO CS polarity must be defined Active High to avoid
+				 * ambiguity. That's why we use enable, that takes SPI_CS_HIGH
+				 * into account.
+				 */
+				if (has_acpi_companion(&spi->dev))
+					gpiod_set_value_cansleep(spi->cs_gpiod, !enable);
+				else
+					/* Polarity handled by GPIO library */
+					gpiod_set_value_cansleep(spi->cs_gpiod, activate);
+			} else {
 				/*
 				 * invert the enable line, as active low is
 				 * default for SPI.
 				 */
 				gpio_set_value_cansleep(spi->cs_gpio, !enable);
+			}
 		}
 		/* Some SPI masters need both GPIO CS & slave_select */
 		if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&