FAILED: patch "[PATCH] mmc: renesas_sdhi_internal_dmac: limit DMA RX for old SoCs" failed to apply to 4.15-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

The patch below does not apply to the 4.15-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 <stable@xxxxxxxxxxxxxxx>.

thanks,

greg k-h

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

>From 0cbc94daa55441c21999e96a07061952d873dcb7 Mon Sep 17 00:00:00 2001
From: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Date: Wed, 18 Apr 2018 20:20:57 +0200
Subject: [PATCH] mmc: renesas_sdhi_internal_dmac: limit DMA RX for old SoCs

Early revisions of certain SoCs cannot do multiple DMA RX streams in
parallel. To avoid data corruption, only allow one DMA RX channel and
fall back to PIO, if needed.

Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Tested-by: Nguyen Viet Dung <dung.nguyen.aj@xxxxxxxxxxx>
Reviewed-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>

diff --git a/drivers/mmc/host/renesas_sdhi_internal_dmac.c b/drivers/mmc/host/renesas_sdhi_internal_dmac.c
index 8e0acd197c43..6af946d16d24 100644
--- a/drivers/mmc/host/renesas_sdhi_internal_dmac.c
+++ b/drivers/mmc/host/renesas_sdhi_internal_dmac.c
@@ -9,6 +9,7 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/io-64-nonatomic-hi-lo.h>
@@ -62,6 +63,17 @@
  *   need a custom accessor.
  */
 
+static unsigned long global_flags;
+/*
+ * Workaround for avoiding to use RX DMAC by multiple channels.
+ * On R-Car H3 ES1.* and M3-W ES1.0, when multiple SDHI channels use
+ * RX DMAC simultaneously, sometimes hundreds of bytes data are not
+ * stored into the system memory even if the DMAC interrupt happened.
+ * So, this driver then uses one RX DMAC channel only.
+ */
+#define SDHI_INTERNAL_DMAC_ONE_RX_ONLY	0
+#define SDHI_INTERNAL_DMAC_RX_IN_USE	1
+
 /* Definitions for sampling clocks */
 static struct renesas_sdhi_scc rcar_gen3_scc_taps[] = {
 	{
@@ -126,6 +138,9 @@ renesas_sdhi_internal_dmac_abort_dma(struct tmio_mmc_host *host) {
 	renesas_sdhi_internal_dmac_dm_write(host, DM_CM_RST,
 					    RST_RESERVED_BITS | val);
 
+	if (host->data && host->data->flags & MMC_DATA_READ)
+		clear_bit(SDHI_INTERNAL_DMAC_RX_IN_USE, &global_flags);
+
 	renesas_sdhi_internal_dmac_enable_dma(host, true);
 }
 
@@ -155,6 +170,9 @@ renesas_sdhi_internal_dmac_start_dma(struct tmio_mmc_host *host,
 	if (data->flags & MMC_DATA_READ) {
 		dtran_mode |= DTRAN_MODE_CH_NUM_CH1;
 		dir = DMA_FROM_DEVICE;
+		if (test_bit(SDHI_INTERNAL_DMAC_ONE_RX_ONLY, &global_flags) &&
+		    test_and_set_bit(SDHI_INTERNAL_DMAC_RX_IN_USE, &global_flags))
+			goto force_pio;
 	} else {
 		dtran_mode |= DTRAN_MODE_CH_NUM_CH0;
 		dir = DMA_TO_DEVICE;
@@ -208,6 +226,9 @@ static void renesas_sdhi_internal_dmac_complete_tasklet_fn(unsigned long arg)
 	renesas_sdhi_internal_dmac_enable_dma(host, false);
 	dma_unmap_sg(&host->pdev->dev, host->sg_ptr, host->sg_len, dir);
 
+	if (dir == DMA_FROM_DEVICE)
+		clear_bit(SDHI_INTERNAL_DMAC_RX_IN_USE, &global_flags);
+
 	tmio_mmc_do_data_irq(host);
 out:
 	spin_unlock_irq(&host->lock);
@@ -251,18 +272,24 @@ static const struct tmio_mmc_dma_ops renesas_sdhi_internal_dmac_dma_ops = {
  * implementation as others may use a different implementation.
  */
 static const struct soc_device_attribute gen3_soc_whitelist[] = {
-        { .soc_id = "r8a7795", .revision = "ES1.*" },
-        { .soc_id = "r8a7795", .revision = "ES2.0" },
-        { .soc_id = "r8a7796", .revision = "ES1.0" },
-        { .soc_id = "r8a77995", .revision = "ES1.0" },
-        { /* sentinel */ }
+	{ .soc_id = "r8a7795", .revision = "ES1.*",
+	  .data = (void *)BIT(SDHI_INTERNAL_DMAC_ONE_RX_ONLY) },
+	{ .soc_id = "r8a7795", .revision = "ES2.0" },
+	{ .soc_id = "r8a7796", .revision = "ES1.0",
+	  .data = (void *)BIT(SDHI_INTERNAL_DMAC_ONE_RX_ONLY) },
+	{ .soc_id = "r8a77995", .revision = "ES1.0" },
+	{ /* sentinel */ }
 };
 
 static int renesas_sdhi_internal_dmac_probe(struct platform_device *pdev)
 {
-	if (!soc_device_match(gen3_soc_whitelist))
+	const struct soc_device_attribute *soc = soc_device_match(gen3_soc_whitelist);
+
+	if (!soc)
 		return -ENODEV;
 
+	global_flags |= (unsigned long)soc->data;
+
 	return renesas_sdhi_probe(pdev, &renesas_sdhi_internal_dmac_dma_ops);
 }