mmc: renesas_sdhi_internal_dmac: mask DMAC interrupts

I have encountered an interrupt storm during the eMMC chip probing (and
the chip finally didn't get detected).  It turned out that U-Boot left
the SDHI DMA interrupts enabled while the Linux driver didn't use those.
Masking those interrupts in renesas_sdhi_internal_dmac_request_dma() gets
rid of both issues...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Fixes: 2a68ea7 ("mmc: renesas-sdhi: add support for R-Car Gen3 SDHI DMAC")
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/renesas_sdhi_internal_dmac.c

@@ -49,10 +49,12 @@
 
 /* DM_CM_INFO1 and DM_CM_INFO1_MASK */
 #define INFO1_CLEAR		0
+#define INFO1_MASK_CLEAR	GENMASK_ULL(31, 0)
 #define INFO1_DTRANEND1		BIT(17)
 #define INFO1_DTRANEND0		BIT(16)
 
 /* DM_CM_INFO2 and DM_CM_INFO2_MASK */
+#define INFO2_MASK_CLEAR	GENMASK_ULL(31, 0)
 #define INFO2_DTRANERR1		BIT(17)
 #define INFO2_DTRANERR0		BIT(16)
 
@@ -252,6 +254,12 @@ renesas_sdhi_internal_dmac_request_dma(struct tmio_mmc_host *host,
 {
 	struct renesas_sdhi *priv = host_to_priv(host);
 
+	/* Disable DMAC interrupts, we don't use them */
+	renesas_sdhi_internal_dmac_dm_write(host, DM_CM_INFO1_MASK,
+					    INFO1_MASK_CLEAR);
+	renesas_sdhi_internal_dmac_dm_write(host, DM_CM_INFO2_MASK,
+					    INFO2_MASK_CLEAR);
+
 	/* Each value is set to non-zero to assume "enabling" each DMA */
 	host->chan_rx = host->chan_tx = (void *)0xdeadbeaf;