[PATCH 2/5] mmc: sdhci-msm: Fix HW issue with power IRQ handling during reset

Vijay Viswanath
2017-08-18T05:19:39Z

From: Sahitya Tummala <stummala@codeaurora.org>

There is a rare scenario in HW, where the first clear pulse could
be lost when the actual reset and clear/read of status register
are happening at the same time. Fix this by retrying upto 10 times
to ensure the status register gets cleared. Otherwise, this will
lead to a spurious power IRQ which results in system instability.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Signed-off-by: Vijay Viswanath <vviswana@codeaurora.org>
---
drivers/mmc/host/sdhci-msm.c | 43 ++++++++++++++++++++++++++++++++++++++++---
1 file changed, 40 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
index 0957199..f3e0489 100644
--- a/drivers/mmc/host/sdhci-msm.c
+++ b/drivers/mmc/host/sdhci-msm.c
@@ -995,17 +995,51 @@ static void sdhci_msm_set_uhs_signaling(struct sdhci_host *host,
sdhci_msm_hs400(host, &mmc->ios);
}

-static void sdhci_msm_voltage_switch(struct sdhci_host *host)
+static void sdhci_msm_dump_pwr_ctrl_regs(struct sdhci_host *host)
+{
+ struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+ struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
+
+ pr_err("%s: PWRCTL_STATUS: 0x%08x | PWRCTL_MASK: 0x%08x | PWRCTL_CTL: 0x%08x\n",
+ mmc_hostname(host->mmc),
+ readl_relaxed(msm_host->core_mem + CORE_PWRCTL_STATUS),
+ readl_relaxed(msm_host->core_mem + CORE_PWRCTL_MASK),
+ readl_relaxed(msm_host->core_mem + CORE_PWRCTL_CTL));
+}
+
+static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
{
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
u32 irq_status, irq_ack = 0;
+ int retry = 10;

irq_status = readl_relaxed(msm_host->core_mem + CORE_PWRCTL_STATUS);
irq_status &= INT_MASK;

writel_relaxed(irq_status, msm_host->core_mem + CORE_PWRCTL_CLEAR);

+ /*
+ * There is a rare HW scenario where the first clear pulse could be
+ * lost when actual reset and clear/read of status register is
+ * happening at a time. Hence, retry for at least 10 times to make
+ * sure status register is cleared. Otherwise, this will result in
+ * a spurious power IRQ resulting in system instability.
+ */
+ while (irq_status & readl_relaxed(msm_host->core_mem +
+ CORE_PWRCTL_STATUS)) {
+ if (retry == 0) {
+ pr_err("%s: Timedout clearing (0x%x) pwrctl status register\n",
+ mmc_hostname(host->mmc), irq_status);
+ sdhci_msm_dump_pwr_ctrl_regs(host);
+ WARN_ON(1);
+ }
+ writel_relaxed(irq_status,
+ msm_host->core_mem + CORE_PWRCTL_CLEAR);
+ retry--;
+ udelay(10);
+ }
+
if (irq_status & (CORE_PWRCTL_BUS_ON | CORE_PWRCTL_BUS_OFF))
irq_ack |= CORE_PWRCTL_BUS_SUCCESS;
if (irq_status & (CORE_PWRCTL_IO_LOW | CORE_PWRCTL_IO_HIGH))
@@ -1017,13 +1051,17 @@ static void sdhci_msm_voltage_switch(struct sdhci_host *host)
* switches are handled by the sdhci core, so just report success.
*/
writel_relaxed(irq_ack, msm_host->core_mem + CORE_PWRCTL_CTL);
+
+ pr_debug("%s: %s: Handled IRQ(%d), irq_status=0x%x, ack=0x%x\n",
+ mmc_hostname(msm_host->mmc), __func__, irq, irq_status,
+ irq_ack);
}

static irqreturn_t sdhci_msm_pwr_irq(int irq, void *data)
{
struct sdhci_host *host = (struct sdhci_host *)data;

- sdhci_msm_voltage_switch(host);
+ sdhci_msm_handle_pwr_irq(host, irq);

return IRQ_HANDLED;
}
@@ -1106,7 +1144,6 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock)
.get_max_clock = sdhci_msm_get_max_clock,
.set_bus_width = sdhci_set_bus_width,
.set_uhs_signaling = sdhci_msm_set_uhs_signaling,
- .voltage_switch = sdhci_msm_voltage_switch,
};

static const struct sdhci_pltfm_data sdhci_msm_pdata = {
--
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