[PATCH] mmc: renesas_sdhi_internal_dmac: mask DMAC interrupts

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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@xxxxxxxxxxxxxxxxxx>

---
The patch is against Ulf Hansson's 'mmc.git' repo's 'fixes' branch.

 drivers/mmc/host/renesas_sdhi_internal_dmac.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

Index: mmc/drivers/mmc/host/renesas_sdhi_internal_dmac.c
===================================================================
--- mmc.orig/drivers/mmc/host/renesas_sdhi_internal_dmac.c
+++ mmc/drivers/mmc/host/renesas_sdhi_internal_dmac.c
@@ -51,10 +51,12 @@
 #define INFO1_CLEAR		0
 #define INFO1_DTRANEND1		BIT(17)
 #define INFO1_DTRANEND0		BIT(16)
+#define INFO1_RESERVED_BITS	GENMASK_ULL(32, 0)
 
 /* DM_CM_INFO2 and DM_CM_INFO2_MASK */
 #define INFO2_DTRANERR1		BIT(17)
 #define INFO2_DTRANERR0		BIT(16)
+#define INFO2_RESERVED_BITS	GENMASK_ULL(32, 0)
 
 /*
  * Specification of this driver:
@@ -236,6 +238,15 @@ renesas_sdhi_internal_dmac_request_dma(s
 {
 	struct renesas_sdhi *priv = host_to_priv(host);
 
+	/*
+	 * We don't use the DMA interrupts,  but they might have been enabled
+	 * by a bootloader,  so mask them to avoid an interrupt storm...
+	 */
+	renesas_sdhi_internal_dmac_dm_write(host, DM_CM_INFO1_MASK,
+					    INFO1_RESERVED_BITS);
+	renesas_sdhi_internal_dmac_dm_write(host, DM_CM_INFO2_MASK,
+					    INFO2_RESERVED_BITS);
+
 	/* Each value is set to non-zero to assume "enabling" each DMA */
 	host->chan_rx = host->chan_tx = (void *)0xdeadbeaf;
 



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