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Patch "serial: samsung: Continue to work if DMA request fails" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Mar 15, 2017

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Stable branch Arm Samsung Exynos TTY layer and serial drivers
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This is a note to let you know that I've just added the patch titled

serial: samsung: Continue to work if DMA request fails

to the 4.4-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:
serial-samsung-continue-to-work-if-dma-request-fails.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From f98c7bce570bdbe344b74ff5daa7dfeef3f22929 Mon Sep 17 00:00:00 2001

From: Krzysztof Kozlowski <[email protected]>
Date: Sat, 25 Feb 2017 18:36:44 +0200
Subject: serial: samsung: Continue to work if DMA request fails
MIME-Version: 1.0
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From: Krzysztof Kozlowski <[email protected]>

commit f98c7bce570bdbe344b74ff5daa7dfeef3f22929 upstream.

If DMA is not available (even when configured in DeviceTree), the driver will fail the startup procedure thus making serial console not available.

For example this causes boot failure on QEMU ARMv7 (Exynos4210, SMDKC210):

    [    1.302575] OF: amba_device_add() failed (-19) for /amba/pdma@12680000
    ...
    [   11.435732] samsung-uart 13800000.serial: DMA request failed
    [   72.963893] samsung-uart 13800000.serial: DMA request failed
    [   73.143361] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000

DMA is not necessary for serial to work, so continue with UART startup after emitting a warning.

Fixes 62c37eedb74c ("serial: samsung: add dma reqest/release functions")
Signed-off-by Krzysztof Kozlowski <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/tty/serial/samsung.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
drivers/tty/serial/samsung.c +4 -2
@@ -1030,8 +1030,10 @@ static int s3c64xx_serial_startup(struct
 	if (ourport->dma) {
 		ret = s3c24xx_serial_request_dma(ourport);
 		if (ret < 0) {
-			dev_warn(port->dev, "DMA request failed\n");
-			return ret;
+			dev_warn(port->dev,
+				 "DMA request failed, DMA will not be used\n");
+			devm_kfree(port->dev, ourport->dma);
+			ourport->dma = NULL;
 		}
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/serial-samsung-continue-to-work-if-dma-request-fails.patch