On Fri, May 9, 2014 at 8:36 PM, Sonny Rao [off-list ref] wrote:

On Fri, May 9, 2014 at 12:32 AM, Jaehoon Chung [off-list ref] wrote:

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Hi, Sonny.

You can discard the my previous some comment.
As you mentioned, this reset sequence is recommended at Synopsys TRM.

Add the minor question.

On 05/09/2014 01:27 PM, Jaehoon Chung wrote:

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Hi, Sonny.

I have checked the Synopsys TRM..

On 05/09/2014 10:34 AM, Sonny Rao wrote:

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On Thu, May 8, 2014 at 6:15 PM, Jaehoon Chung [off-list ref] wrote:

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On 05/08/2014 06:40 PM, Yuvaraj Kumar wrote:

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Any comments on this patch?

On Wed, Mar 26, 2014 at 5:16 PM, Yuvaraj Kumar C D [off-list ref] wrote:

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From: Sonny Rao <redacted>

This patch changes the fifo reset code to follow the reset procedure
outlined in the documentation of Synopsys  Mobile storage host databook
7.2.13.
Without this patch, we could able to see eMMC was not detected after
multiple reboots due to driver hangs while eMMC tuning for HS200.

Signed-off-by: Sonny Rao <redacted>
Signed-off-by: Yuvaraj Kumar C D <redacted>
---
 drivers/mmc/host/dw_mmc.c |   48 ++++++++++++++++++++++++++++++++++++++++++++-
 drivers/mmc/host/dw_mmc.h |    1 +
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 32dd81d..1d77431 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c

@@ -2220,7 +2220,53 @@ static inline bool dw_mci_fifo_reset(struct dw_mci *host)
                host->sg = NULL;
        }

-       return dw_mci_ctrl_reset(host, SDMMC_CTRL_FIFO_RESET);
+       /*
+        * The recommended method for resetting is to always reset the
+        * controller and the fifo, but differs slightly depending on the mode.
+        * Note that this doesn't handle the "generic DMA" (not IDMAC) case.
+        */

"not IDMAC" is confused..

The documentation describes three different possible modes.  There's a
mode that doesn't use IDMAC but still does DMA.  But as far as I can
tell this driver doesn't support that way.  We can just remove that
wording if it's confusing.

How did it know whether dma is generic DMA or not?

That's a good question.  I wasn't sure whether the driver supported it
or not.  It looks like it definitely supports IDMAC through the
CONFIG_MMC_DW_IDMAC flag, but I wasn't sure if it was supported the
generic dma.  Maybe if CONFIG_MMC_DW_IDMAC isn't specified but
host->dma_ops is not NULL then we are using the generic dma mode.

Doug mentioned that James Hogan might have an answer.  James, are
there Imgtec SoCs which use dw_mmc and use DMA but don't use the
IDMAC?  If so, we can add that support into this reset procedure
patch.

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+       if (dw_mci_ctrl_reset(host, SDMMC_CTRL_RESET | SDMMC_CTRL_FIFO_RESET)) {
+               unsigned long timeout = jiffies + msecs_to_jiffies(500);
+               u32 status, rint;
+
+               /* if using dma we wait for dma_req to clear */
+               if (host->using_dma) {
+                       do {
+                               status = mci_readl(host, STATUS);
+                               if (!(status & SDMMC_STATUS_DMA_REQ))
+                                       break;
+                               cpu_relax();
+                       } while (time_before(jiffies, timeout));
+
+                       if (status & SDMMC_STATUS_DMA_REQ)
+                               dev_err(host->dev,
+                                       "%s: Timeout waiting for dma_req to "
+                                       "clear during reset", __func__);
+
+                       /* when using DMA next we reset the fifo again */
+                       dw_mci_ctrl_reset(host, SDMMC_CTRL_FIFO_RESET);
+               }
+               /*
+                * In all cases we clear the RAWINTS register to clear any
+                * interrupts.
+                */
+               rint = mci_readl(host, RINTSTS);
+               rint = rint & (~mci_readl(host, MINTSTS));

you use the "status or temp" instead of rint. (you can reuse the variable.)
And can use "status &= ~mci_readl(host,MINTSTS);"

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Just clear the RINTSTS register? why do you add these?

This will look at what is not masked, and only clear those bits.

Well, i known if clear the RINTSTS register,
recommended to use "0xfffffff" and set the value for interrupt.

Can be used "0xfffffff"?

Yeah we probably can.  We just lose information about interrupts that
were masked, but maybe we just don't care about any of them anyway, so
it doesn't matter.

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Best Regards,
Jaehoon Chung

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+               if (rint)
+                       mci_writel(host, RINTSTS, rint);
+
+       } else
+               dev_err(host->dev, "%s: Reset bits didn't clear", __func__);

Just display the error log? I didn't understand this.
If you displayed the error log, then it needs to return the error value.

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+
+ #ifdef CONFIG_MMC_DW_IDMAC
+       /* It is also recommended that we reset and reprogram idmac */
+       dw_mci_idmac_reset(host);
+ #endif
+
+       /* After a CTRL reset we need to have CIU set clock registers  */
+       mci_send_cmd(host->cur_slot, SDMMC_CMD_UPD_CLK, 0);

Well, why do you send the clock update command?
I didn't see that update the value related with clock.

Best Regards,
Jaehoon Chung

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+
+       return true;
 }

 static inline bool dw_mci_ctrl_all_reset(struct dw_mci *host)

diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
index 738fa24..037e47a 100644
--- a/drivers/mmc/host/dw_mmc.h
+++ b/drivers/mmc/host/dw_mmc.h

@@ -129,6 +129,7 @@
 #define SDMMC_CMD_INDX(n)              ((n) & 0x1F)
 /* Status register defines */
 #define SDMMC_GET_FCNT(x)              (((x)>>17) & 0x1FFF)
+#define SDMMC_STATUS_DMA_REQ           BIT(31)
 /* FIFOTH register defines */
 #define SDMMC_SET_FIFOTH(m, r, t)      (((m) & 0x7) << 28 | \
                                         ((r) & 0xFFF) << 16 | \
--

1.7.10.4

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