Potential patch to work around occasional SDHOST timeouts

0001-bcm2835-sdhost-Reset-controller-DMA-on-timeout.patch

From 84b0474a86349d36a943db70acdde4729f66478e Mon Sep 17 00:00:00 2001
From: Phil Elwell <[email protected]>
Date: Thu, 22 Feb 2018 17:18:32 +0000
Subject: [PATCH] bcm2835-sdhost: Reset controller & DMA on timeout

Under some circumstances the SDHOST controller has been observed to
lock up, leading to a timeout. When this happens, give the system a
chance of recovering by resetting the controller and terminating any
DMA transfer.

Largely copied from a patch to the upstream bcm2835 driver by
Michal Suchanek <[email protected]>.

See: https://github.com/raspberrypi/issues/2392

Signed-off-by: Phil Elwell <[email protected]>
---
 drivers/mmc/host/bcm2835-sdhost.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/mmc/host/bcm2835-sdhost.c b/drivers/mmc/host/bcm2835-sdhost.c
index 273b1be..6b6bcc0 100644
--- a/drivers/mmc/host/bcm2835-sdhost.c
+++ b/drivers/mmc/host/bcm2835-sdhost.c
@@ -416,6 +416,10 @@ static void bcm2835_sdhost_reset_internal(struct bcm2835_host *host)
 	if (host->debug)
 		pr_info("%s: reset\n", mmc_hostname(host->mmc));
 
+	if (host->dma_chan)
+		dmaengine_terminate_sync(host->dma_chan);
+	host->dma_chan = NULL;
+
 	bcm2835_sdhost_set_power(host, false);
 
 	bcm2835_sdhost_write(host, 0, SDCMD);
@@ -1320,6 +1324,8 @@ static void bcm2835_sdhost_timeout(unsigned long data)
 		log_dump();
 		bcm2835_sdhost_dumpregs(host);
 
+		bcm2835_sdhost_reset_internal(host);
+
 		if (host->data) {
 			host->data->error = -ETIMEDOUT;
 			bcm2835_sdhost_finish_data(host);
-- 
2.7.4