Re: [PATCH] mmc: dw_mmc: init desc in dw_mci_idmac_init

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On 04/30/2015 04:01 PM, Jaehoon Chung wrote:
Hi.

On 04/29/2015 10:31 PM, Zhangfei Gao wrote:
Set 0 to des1 in 32bit case.
Otherwise the random value of des1 will be used in
dw_mci_translate_sglist: IDMAC_64ADDR_SET_BUFFER1_SIZE(desc, length)

I'm not understanding this comment.
how does it use the IDMAC_64ADDR_SET_BUFFER1_SIZE(desc, length)?

p->des1 contains random value, coming from dmam_alloc_coherent in dw_mci_init_dma

In dw_mci_translate_sglist -> IDMAC_SET_BUFFER1_SIZE(desc, length);
#define IDMAC_SET_BUFFER1_SIZE(d, s) \
        ((d)->des1 = ((d)->des1 & 0x03ffe000) | ((s) & 0x1fff))

The random value will be set to des1 as well as length, causing unexpected behavior.

So des1 need to be init to 0.
While des0, des2, des3 are set in dw_mci_idmac_init and dw_mci_translate_sglist.

Thanks



Best Regards,
Jaehoon Chung

Signed-off-by: Fei Wang <w.f@xxxxxxxxxx>
Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
---
  drivers/mmc/host/dw_mmc.c | 4 +++-
  1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 241454f..488a8af 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -589,9 +589,11 @@ static int dw_mci_idmac_init(struct dw_mci *host)
  		host->ring_size = PAGE_SIZE / sizeof(struct idmac_desc);

  		/* Forward link the descriptor list */
-		for (i = 0, p = host->sg_cpu; i < host->ring_size - 1; i++, p++)
+		for (i = 0, p = host->sg_cpu; i < host->ring_size - 1; i++, p++) {
  			p->des3 = cpu_to_le32(host->sg_dma +
  					(sizeof(struct idmac_desc) * (i + 1)));
+			p->des1 = 0;
+		}

  		/* Set the last descriptor as the end-of-ring descriptor */
  		p->des3 = cpu_to_le32(host->sg_dma);


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