sdio: put active devices into 1-bit mode during suspend

And bring them back to 4-bit mode during resume.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 5840de106b69..2dd4cfe7ca17 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -188,6 +188,40 @@ static int sdio_disable_cd(struct mmc_card *card)
 }
 
 /*
+ * Devices that remain active during a system suspend are
+ * put back into 1-bit mode.
+ */
+static int sdio_disable_wide(struct mmc_card *card)
+{
+        int ret;
+        u8 ctrl;
+
+        if (!(card->host->caps & MMC_CAP_4_BIT_DATA))
+                return 0;
+
+        if (card->cccr.low_speed && !card->cccr.wide_bus)
+                return 0;
+
+        ret = mmc_io_rw_direct(card, 0, 0, SDIO_CCCR_IF, 0, &ctrl);
+        if (ret)
+                return ret;
+
+        if (!(ctrl & SDIO_BUS_WIDTH_4BIT))
+                return 0;
+
+        ctrl &= ~SDIO_BUS_WIDTH_4BIT;
+        ctrl |= SDIO_BUS_ASYNC_INT;
+
+        ret = mmc_io_rw_direct(card, 1, 0, SDIO_CCCR_IF, ctrl, NULL);
+        if (ret)
+                return ret;
+
+        mmc_set_bus_width(card->host, MMC_BUS_WIDTH_1);
+
+        return 0;
+}
+
+/*
  * Test if the card supports high-speed mode and, if so, switch to it.
  */
 static int sdio_enable_hs(struct mmc_card *card)
@@ -427,6 +461,12 @@ static int mmc_sdio_suspend(struct mmc_host *host)
                 }
         }
 
+        if (!err && host->pm_flags & MMC_PM_KEEP_POWER) {
+                mmc_claim_host(host);
+                sdio_disable_wide(host->card);
+                mmc_release_host(host);
+        }
+
         return err;
 }
 
@@ -441,6 +481,9 @@ static int mmc_sdio_resume(struct mmc_host *host)
         mmc_claim_host(host);
         err = mmc_sdio_init_card(host, host->ocr, host->card,
                                  (host->pm_flags & MMC_PM_KEEP_POWER));
+        if (!err)
+                /* We may have switched to 1-bit mode during suspend. */
+                err = sdio_enable_wide(host->card);
         if (!err && host->sdio_irqs)
                 mmc_signal_sdio_irq(host);
         mmc_release_host(host);