Patch "spi: sync up initial chipselect state" has been added to the 5.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    spi: sync up initial chipselect state

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     spi-sync-up-initial-chipselect-state.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 1534b9cac3b99a7f5564c8f27e261a0dd4e32b21
Author: David Bauer <mail@xxxxxxxxxxxxxxx>
Date:   Fri Apr 16 21:59:56 2021 +0200

    spi: sync up initial chipselect state
    
    [ Upstream commit d347b4aaa1a042ea528e385d9070b74c77a14321 ]
    
    When initially probing the SPI slave device, the call for disabling an
    SPI device without the SPI_CS_HIGH flag is not applied, as the
    condition for checking whether or not the state to be applied equals the
    one currently set evaluates to true.
    
    This however might not necessarily be the case, as the chipselect might
    be active.
    
    Add a force flag to spi_set_cs which allows to override this
    early exit condition. Set it to false everywhere except when called
    from spi_setup to sync up the initial CS state.
    
    Fixes commit d40f0b6f2e21 ("spi: Avoid setting the chip select if we don't
    need to")
    
    Signed-off-by: David Bauer <mail@xxxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20210416195956.121811-1-mail@xxxxxxxxxxxxxxx
    Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 4257a2d368f7..1eee8b3c1b38 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -787,7 +787,7 @@ int spi_register_board_info(struct spi_board_info const *info, unsigned n)
 
 /*-------------------------------------------------------------------------*/
 
-static void spi_set_cs(struct spi_device *spi, bool enable)
+static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
 {
 	bool enable1 = enable;
 
@@ -795,7 +795,7 @@ static void spi_set_cs(struct spi_device *spi, bool enable)
 	 * Avoid calling into the driver (or doing delays) if the chip select
 	 * isn't actually changing from the last time this was called.
 	 */
-	if ((spi->controller->last_cs_enable == enable) &&
+	if (!force && (spi->controller->last_cs_enable == enable) &&
 	    (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH)))
 		return;
 
@@ -1243,7 +1243,7 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
 	struct spi_statistics *statm = &ctlr->statistics;
 	struct spi_statistics *stats = &msg->spi->statistics;
 
-	spi_set_cs(msg->spi, true);
+	spi_set_cs(msg->spi, true, false);
 
 	SPI_STATISTICS_INCREMENT_FIELD(statm, messages);
 	SPI_STATISTICS_INCREMENT_FIELD(stats, messages);
@@ -1311,9 +1311,9 @@ fallback_pio:
 					 &msg->transfers)) {
 				keep_cs = true;
 			} else {
-				spi_set_cs(msg->spi, false);
+				spi_set_cs(msg->spi, false, false);
 				_spi_transfer_cs_change_delay(msg, xfer);
-				spi_set_cs(msg->spi, true);
+				spi_set_cs(msg->spi, true, false);
 			}
 		}
 
@@ -1322,7 +1322,7 @@ fallback_pio:
 
 out:
 	if (ret != 0 || !keep_cs)
-		spi_set_cs(msg->spi, false);
+		spi_set_cs(msg->spi, false, false);
 
 	if (msg->status == -EINPROGRESS)
 		msg->status = ret;
@@ -3400,11 +3400,11 @@ int spi_setup(struct spi_device *spi)
 		 */
 		status = 0;
 
-		spi_set_cs(spi, false);
+		spi_set_cs(spi, false, true);
 		pm_runtime_mark_last_busy(spi->controller->dev.parent);
 		pm_runtime_put_autosuspend(spi->controller->dev.parent);
 	} else {
-		spi_set_cs(spi, false);
+		spi_set_cs(spi, false, true);
 	}
 
 	mutex_unlock(&spi->controller->io_mutex);