linux-kernel - [PATCH] spi: Restore delays for non-GPIO chip select

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Date: Mon, 11 Mar 2024 23:53:17 +0100
From: Janne Grunau via B4 Relay <devnull+j.jannau.net@...nel.org>
To: Mark Brown <broonie@...nel.org>, 
 Amit Kumar Mahapatra <amit.kumar-mahapatra@....com>
Cc: linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 asahi@...ts.linux.dev, regressions@...ts.linux.dev, 
 Janne Grunau <j@...nau.net>
Subject: [PATCH] spi: Restore delays for non-GPIO chip select

From: Janne Grunau <j@...nau.net>

SPI controller with integrated chip select handling still need to adhere
to SPI device's CS setup, hold and inactive delays. For controller
without set_cs_timing spi core shall handle the delays to avoid
duplicated delay handling in each controller driver.
Fixes a regression for the out of tree SPI controller and SPI HID
transport on Apple M1/M1 Pro/Max notebooks.

Fixes: 4d8ff6b0991d ("spi: Add multi-cs memories support in SPI core")
Signed-off-by: Janne Grunau <j@...nau.net>
---
#regzbot ^introduced 4d8ff6b0991d5e86b17b235fc46ec62e9195cb9
---
 drivers/spi/spi.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index f2170f4b5077..71be2ba8402f 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1042,10 +1042,14 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
 	if (spi->mode & SPI_CS_HIGH)
 		enable = !enable;
 
-	if (spi_is_csgpiod(spi)) {
-		if (!spi->controller->set_cs_timing && !activate)
-			spi_delay_exec(&spi->cs_hold, NULL);
+	/*
+	 * Handle chip select delays for GPIO based CS or controllers without
+	 * programmable chip select timing.
+	 */
+	if ((spi_is_csgpiod(spi) || !spi->controller->set_cs_timing) && !activate)
+		spi_delay_exec(&spi->cs_hold, NULL);
 
+	if (spi_is_csgpiod(spi)) {
 		if (!(spi->mode & SPI_NO_CS)) {
 			/*
 			 * Historically ACPI has no means of the GPIO polarity and
@@ -1079,16 +1083,16 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
 		if ((spi->controller->flags & SPI_CONTROLLER_GPIO_SS) &&
 		    spi->controller->set_cs)
 			spi->controller->set_cs(spi, !enable);
-
-		if (!spi->controller->set_cs_timing) {
-			if (activate)
-				spi_delay_exec(&spi->cs_setup, NULL);
-			else
-				spi_delay_exec(&spi->cs_inactive, NULL);
-		}
 	} else if (spi->controller->set_cs) {
 		spi->controller->set_cs(spi, !enable);
 	}
+
+	if (spi_is_csgpiod(spi) || !spi->controller->set_cs_timing) {
+		if (activate)
+			spi_delay_exec(&spi->cs_setup, NULL);
+		else
+			spi_delay_exec(&spi->cs_inactive, NULL);
+	}
 }
 
 #ifdef CONFIG_HAS_DMA

---
base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
change-id: 20240311-spi-cs-delays-regression-fd7309fc0eff

Best regards,
-- 
Janne Grunau <j@...nau.net>