mmc_sdio_power_restore() skips some steps that are performed in other
power-related codepaths which are necessary to fully reset the card.
Without this, runtime PM fails for SD8686 SDIO wifi on OLPC XO-1.5.
Signed-off-by: Daniel Drake <dsd@xxxxxxxxxx>
---
drivers/mmc/core/sdio.c | 39 +++++++++++++++++++++++++++++++++++++++
1 files changed, 39 insertions(+), 0 deletions(-)
Replaces existing patch with the same name
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 4d0c15b..262fff0 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -691,15 +691,54 @@ static int mmc_sdio_resume(struct mmc_host *host)
static int mmc_sdio_power_restore(struct mmc_host *host)
{
int ret;
+ u32 ocr;
BUG_ON(!host);
BUG_ON(!host->card);
mmc_claim_host(host);
+
+ /*
+ * Reset the card by performing the same steps that are taken by
+ * mmc_rescan_try_freq() and mmc_attach_sdio() during a "normal" probe.
+ *
+ * sdio_reset() is technically not needed. Having just powered up the
+ * hardware, it should already be in reset state. However, some
+ * platforms (such as SD8686 on OLPC) do not instantly cut power,
+ * meaning that a reset is required when restoring power soon after
+ * powering off. It is harmless in other cases.
+ *
+ * The CMD5 reset (mmc_send_io_op_cond()), according to the SDIO spec,
+ * is not necessary for non-removable cards. However, it is required
+ * for OLPC SD8686 (which expects a [CMD5,5,3,7] init sequence), and
+ * harmless in other situations.
+ *
+ * With these steps taken, mmc_select_voltage() is also required to
+ * restore the correct voltage setting of the card.
+ */
+ sdio_reset(host);
+ mmc_go_idle(host);
+ mmc_send_if_cond(host, host->ocr_avail);
+
+ ret = mmc_send_io_op_cond(host, 0, &ocr);
+ if (ret)
+ goto out;
+
+ if (host->ocr_avail_sdio)
+ host->ocr_avail = host->ocr_avail_sdio;
+
+ host->ocr = mmc_select_voltage(host, ocr & ~0x7F);
+ if (!host->ocr) {
+ ret = -EINVAL;
+ goto out;
+ }
+
ret = mmc_sdio_init_card(host, host->ocr, host->card,
mmc_card_keep_power(host));
if (!ret && host->sdio_irqs)
mmc_signal_sdio_irq(host);
+
+out:
mmc_release_host(host);
return ret;
--
1.7.5.4
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