--- /dev/null
+From 969872e334937bd0956887a925f20f7a446af5f6 Mon Sep 17 00:00:00 2001
+From: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
+Date: Thu, 25 Jun 2015 11:25:07 +0300
+Subject: [PATCH] mmc: dw_mmc: handle data blocks > than 4kB if IDMAC is used
+
+As per DW MobileStorage databook "each descriptor can transfer up to 4kB
+of data in chained mode", moreover buffer size that is put in "des1" is
+limited to 13 bits, i.e. for example on attempt to
+IDMAC_SET_BUFFER1_SIZE(desc, 8192) size value that's effectively written
+will be 0.
+
+On the platform with 8kB PAGE_SIZE I see dw_mmc gets data blocks in
+SG-list of 8kB size and that leads to unpredictable behavior of the
+SD/MMC controller.
+
+In particular on write to FAT partition of SD-card the controller will
+stuck in the middle of DMA transaction.
+
+Solution to the problem is simple - we need to pass large (> 4kB) data
+buffers to the controller via multiple descriptors. And that's what
+that change does.
+
+What's interesting I did try original driver on same platform but
+configured with 4kB PAGE_SIZE and may confirm that data blocks passed
+in SG-list to dw_mmc never exeed 4kB limit - that explains why nobody
+ever faced a problem I did.
+
+Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
+Cc: Seungwon Jeon <tgih.jun@samsung.com>
+Cc: Jaehoon Chung <jh80.chung@samsung.com>
+Cc: Ulf Hansson <ulf.hansson@linaro.org>
+Cc: arc-linux-dev@synopsys.com
+Cc: linux-kernel@vger.kernel.org
+Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
+---
+ drivers/mmc/host/dw_mmc.c | 109 ++++++++++++++++++++++++++++++----------------
+ 1 file changed, 71 insertions(+), 38 deletions(-)
+
+diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
+index 40e9d8e..e41fb74 100644
+--- a/drivers/mmc/host/dw_mmc.c
++++ b/drivers/mmc/host/dw_mmc.c
+@@ -99,6 +99,9 @@ struct idmac_desc {
+
+ __le32 des3; /* buffer 2 physical address */
+ };
++
++/* Each descriptor can transfer up to 4KB of data in chained mode */
++#define DW_MCI_DESC_DATA_LENGTH 0x1000
+ #endif /* CONFIG_MMC_DW_IDMAC */
+
+ static bool dw_mci_reset(struct dw_mci *host);
+@@ -462,66 +465,96 @@ static void dw_mci_idmac_complete_dma(struct dw_mci *host)
+ static void dw_mci_translate_sglist(struct dw_mci *host, struct mmc_data *data,
+ unsigned int sg_len)
+ {
++ unsigned int desc_len;
+ int i;
+ if (host->dma_64bit_address == 1) {
+- struct idmac_desc_64addr *desc = host->sg_cpu;
++ struct idmac_desc_64addr *desc_first, *desc_last, *desc;
++
++ desc_first = desc_last = desc = host->sg_cpu;
+
+- for (i = 0; i < sg_len; i++, desc++) {
++ for (i = 0; i < sg_len; i++) {
+ unsigned int length = sg_dma_len(&data->sg[i]);
+ u64 mem_addr = sg_dma_address(&data->sg[i]);
+
+- /*
+- * Set the OWN bit and disable interrupts for this
+- * descriptor
+- */
+- desc->des0 = IDMAC_DES0_OWN | IDMAC_DES0_DIC |
+- IDMAC_DES0_CH;
+- /* Buffer length */
+- IDMAC_64ADDR_SET_BUFFER1_SIZE(desc, length);
+-
+- /* Physical address to DMA to/from */
+- desc->des4 = mem_addr & 0xffffffff;
+- desc->des5 = mem_addr >> 32;
++ for ( ; length ; desc++) {
++ desc_len = (length <= DW_MCI_DESC_DATA_LENGTH) ?
++ length : DW_MCI_DESC_DATA_LENGTH;
++
++ length -= desc_len;
++
++ /*
++ * Set the OWN bit and disable interrupts
++ * for this descriptor
++ */
++ desc->des0 = IDMAC_DES0_OWN | IDMAC_DES0_DIC |
++ IDMAC_DES0_CH;
++
++ /* Buffer length */
++ IDMAC_64ADDR_SET_BUFFER1_SIZE(desc, desc_len);
++
++ /* Physical address to DMA to/from */
++ desc->des4 = mem_addr & 0xffffffff;
++ desc->des5 = mem_addr >> 32;
++
++ /* Update physical address for the next desc */
++ mem_addr += desc_len;
++
++ /* Save pointer to the last descriptor */
++ desc_last = desc;
++ }
+ }
+
+ /* Set first descriptor */
+- desc = host->sg_cpu;
+- desc->des0 |= IDMAC_DES0_FD;
++ desc_first->des0 |= IDMAC_DES0_FD;
+
+ /* Set last descriptor */
+- desc = host->sg_cpu + (i - 1) *
+- sizeof(struct idmac_desc_64addr);
+- desc->des0 &= ~(IDMAC_DES0_CH | IDMAC_DES0_DIC);
+- desc->des0 |= IDMAC_DES0_LD;
++ desc_last->des0 &= ~(IDMAC_DES0_CH | IDMAC_DES0_DIC);
++ desc_last->des0 |= IDMAC_DES0_LD;
+
+ } else {
+- struct idmac_desc *desc = host->sg_cpu;
++ struct idmac_desc *desc_first, *desc_last, *desc;
++
++ desc_first = desc_last = desc = host->sg_cpu;
+
+- for (i = 0; i < sg_len; i++, desc++) {
++ for (i = 0; i < sg_len; i++) {
+ unsigned int length = sg_dma_len(&data->sg[i]);
+ u32 mem_addr = sg_dma_address(&data->sg[i]);
+
+- /*
+- * Set the OWN bit and disable interrupts for this
+- * descriptor
+- */
+- desc->des0 = cpu_to_le32(IDMAC_DES0_OWN |
+- IDMAC_DES0_DIC | IDMAC_DES0_CH);
+- /* Buffer length */
+- IDMAC_SET_BUFFER1_SIZE(desc, length);
++ for ( ; length ; desc++) {
++ desc_len = (length <= DW_MCI_DESC_DATA_LENGTH) ?
++ length : DW_MCI_DESC_DATA_LENGTH;
++
++ length -= desc_len;
++
++ /*
++ * Set the OWN bit and disable interrupts
++ * for this descriptor
++ */
++ desc->des0 = cpu_to_le32(IDMAC_DES0_OWN |
++ IDMAC_DES0_DIC |
++ IDMAC_DES0_CH);
++
++ /* Buffer length */
++ IDMAC_SET_BUFFER1_SIZE(desc, desc_len);
+
+- /* Physical address to DMA to/from */
+- desc->des2 = cpu_to_le32(mem_addr);
++ /* Physical address to DMA to/from */
++ desc->des2 = cpu_to_le32(mem_addr);
++
++ /* Update physical address for the next desc */
++ mem_addr += desc_len;
++
++ /* Save pointer to the last descriptor */
++ desc_last = desc;
++ }
+ }
+
+ /* Set first descriptor */
+- desc = host->sg_cpu;
+- desc->des0 |= cpu_to_le32(IDMAC_DES0_FD);
++ desc_first->des0 |= cpu_to_le32(IDMAC_DES0_FD);
+
+ /* Set last descriptor */
+- desc = host->sg_cpu + (i - 1) * sizeof(struct idmac_desc);
+- desc->des0 &= cpu_to_le32(~(IDMAC_DES0_CH | IDMAC_DES0_DIC));
+- desc->des0 |= cpu_to_le32(IDMAC_DES0_LD);
++ desc_last->des0 &= cpu_to_le32(~(IDMAC_DES0_CH |
++ IDMAC_DES0_DIC));
++ desc_last->des0 |= cpu_to_le32(IDMAC_DES0_LD);
+ }
+
+ wmb();
+@@ -2394,7 +2427,7 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
+ #ifdef CONFIG_MMC_DW_IDMAC
+ mmc->max_segs = host->ring_size;
+ mmc->max_blk_size = 65536;
+- mmc->max_seg_size = 0x1000;
++ mmc->max_seg_size = DW_MCI_DESC_DATA_LENGTH;
+ mmc->max_req_size = mmc->max_seg_size * host->ring_size;
+ mmc->max_blk_count = mmc->max_req_size / 512;
+ #else
+--
+2.4.3
+
projects / buildroot.git / commitdiff