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

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On 8/24/2017 1:12 PM, Adrian Hunter wrote:
On 18/08/17 08:19, Vijay Viswanath wrote:
From: Sahitya Tummala <stummala@xxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxx>
Signed-off-by: Vijay Viswanath <vviswana@xxxxxxxxxxxxxx>
---
  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);

Is it your intention to loop forever here?

A bad mistake from my side. Will add break here.
+		}
+		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 = {


--
To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [Linux for Sparc]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux