linux-kernel - [RFC][PATCH] MMC: Use write timeout value as read from CSR

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Message-ID: <5ff4a1e50809010812i32168136qea538ba177b81446@mail.gmail.com>
Date:	Mon, 1 Sep 2008 16:12:03 +0100
From:	"Matt Fleming" <mattjfleming@...glemail.com>
To:	linux-kernel@...r.kernel.org, drzeus-mmc@...eus.cx,
	dbrownell@...rs.sourceforge.net
Subject: [RFC][PATCH] MMC: Use write timeout value as read from CSR

Currently, the MMC/SD over SPI code has a hard-coded timeout value of
250ms on writes. This is correct for SD cards and is specified in the
spec, but it is not correct for MMC cards. For MMC cards the values
that is read from the CSR should be used.

There is already code to ensure that the write timeout value for SD
cards does not exceed 250ms, this patch only affects the MMC case.

diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c
index 7503b81..2818837 100644
--- a/drivers/mmc/host/mmc_spi.c
+++ b/drivers/mmc/host/mmc_spi.c
@@ -34,6 +34,7 @@

 #include <linux/mmc/host.h>
 #include <linux/mmc/mmc.h>             /* for R1_SPI_* bit values */
+#include <linux/mmc/card.h>

 #include <linux/spi/spi.h>
 #include <linux/spi/mmc_spi.h>
@@ -96,7 +97,6 @@
  * shorter timeouts ... but why bother?
  */
 #define readblock_timeout      ktime_set(0, 100 * 1000 * 1000)
-#define writeblock_timeout     ktime_set(0, 250 * 1000 * 1000)
 #define r1b_timeout            ktime_set(3, 0)


@@ -225,6 +225,20 @@ static int mmc_spi_readtoken(struct mmc_spi_host *host)
        return mmc_spi_skip(host, readblock_timeout, 1, 0xff);
 }

+/*
+ * Return the write timeout value (in nanoseconds) for this card.
+ */
+static inline unsigned int
+mmc_get_write_timeout(struct mmc_spi_host *host, struct mmc_data *data)
+{
+       unsigned int timeout_ns;
+
+       timeout_ns = data->timeout_ns;
+       timeout_ns += data->timeout_clks * 1000  * 1000 /
+               (host->mmc->card->host->ios.clock);
+
+       return timeout_ns;
+}

 /*
  * Note that for SPI, cmd->resp[0] is not the same data as "native" protocol
@@ -605,11 +619,13 @@ mmc_spi_setup_data_message(
  * Return negative errno, else success.
  */
 static int
-mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t)
+mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t,
+       struct mmc_data *data)
 {
        struct spi_device       *spi = host->spi;
        int                     status, i;
        struct scratch          *scratch = host->data;
+       unsigned int            timeout_ns;

        if (host->mmc->use_spi_crc)
                scratch->crc_val = cpu_to_be16(
@@ -673,7 +689,11 @@ mmc_spi_writeblock(struct mmc_spi_host *host,
struct spi_transfer *t)
                if (scratch->status[i] != 0)
                        return 0;
        }
-       return mmc_spi_wait_unbusy(host, writeblock_timeout);
+
+       timeout_ns = mmc_get_write_timeout(host, data);
+
+       return mmc_spi_wait_unbusy(host,
+               ktime_add_ns(ktime_set(0, 0), timeout_ns));
 }

 /*
@@ -832,7 +852,7 @@ mmc_spi_data_do(struct mmc_spi_host *host, struct
mmc_command *cmd,
                                t->len);

                        if (direction == DMA_TO_DEVICE)
-                               status = mmc_spi_writeblock(host, t);
+                               status = mmc_spi_writeblock(host, t, data);
                        else
                                status = mmc_spi_readblock(host, t);
                        if (status < 0)
@@ -872,6 +892,7 @@ mmc_spi_data_do(struct mmc_spi_host *host, struct
mmc_command *cmd,
                struct scratch  *scratch = host->data;
                int             tmp;
                const unsigned  statlen = sizeof(scratch->status);
+               unsigned int    timeout_ns;

                dev_dbg(&spi->dev, "    mmc_spi: STOP_TRAN\n");

@@ -917,7 +938,9 @@ mmc_spi_data_do(struct mmc_spi_host *host, struct
mmc_command *cmd,
                        if (scratch->status[tmp] != 0)
                                return;
                }
-               tmp = mmc_spi_wait_unbusy(host, writeblock_timeout);
+               timeout_ns = mmc_get_write_timeout(host, data);
+               tmp = mmc_spi_wait_unbusy(host,
+                       ktime_add_ns(ktime_set(0, 0), timeout_ns));
                if (tmp < 0 && !data->error)
                        data->error = tmp;
        }

View attachment "mmc-spi-use-timeout-from-card.patch" of type "text/x-diff" (2955 bytes)