Re: [PATCH v1] mmc: sdhci_am654: Add sdhci_am654_start_signal_voltage_switch

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Hi Adrian,

On 9/10/24 12:10 PM, Adrian Hunter wrote:
On 10/09/24 17:30, Judith Mendez wrote:
Hi Adrian,

On 9/9/24 1:26 AM, Adrian Hunter wrote:
On 6/09/24 20:50, Judith Mendez wrote:
The sdhci_start_signal_voltage_switch function sets
V1P8_SIGNAL_ENA by default after switching to 1v8 signaling.
V1P8_SIGNAL_ENA determines whether to launch cmd/data on neg
edge or pos edge of clock.

Due to some eMMC and SD failures seen across am62x platform,
do not set V1P8_SIGNAL_ENA by default, only enable the bit
for devices that require this bit in order to switch to 1v8
voltage for uhs modes.

Signed-off-by: Judith Mendez <jm@xxxxxx>
---
   drivers/mmc/host/sdhci_am654.c | 86 ++++++++++++++++++++++++++++++++++
   1 file changed, 86 insertions(+)

diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
index 0aa3c40ea6ed8..fb6232e56606b 100644
--- a/drivers/mmc/host/sdhci_am654.c
+++ b/drivers/mmc/host/sdhci_am654.c
@@ -155,6 +155,7 @@ struct sdhci_am654_data {
       u32 tuning_loop;
     #define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
+#define SDHCI_AM654_QUIRK_SET_V1P8_ENA BIT(1)

It would be better for the quirk to represent the deviation
from normal i.e.

#define SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA BIT(1)

   };
     struct window {
@@ -356,6 +357,79 @@ static void sdhci_j721e_4bit_set_clock(struct sdhci_host *host,
       sdhci_set_clock(host, clock);
   }
   +int sdhci_am654_start_signal_voltage_switch(struct mmc_host *mmc,
+                        struct mmc_ios *ios)

Simpler to call sdhci_start_signal_voltage_switch() for the normal
case e.g.

This is simpler, so sure will use thanks.


static int sdhci_am654_start_signal_voltage_switch(struct mmc_host *mmc, struct mmc_ios *ios)
{
     struct sdhci_host *host = mmc_priv(mmc);
     struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
     struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);


     if ((sdhci_am654->quirks & SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA) &&
         ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180) {
         ret = mmc_regulator_set_vqmmc(mmc, ios);
         if (ret < 0) {
             pr_warn("%s: Switching to 1.8V signalling voltage failed\n",
                 mmc_hostname(mmc));
             return -EIO;
         }
         return 0;
     }

     return sdhci_start_signal_voltage_switch(mmc, ios);
}

+{
+    struct sdhci_host *host = mmc_priv(mmc);
+    struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+    struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
+    u16 ctrl;
+    int ret;
+
+    if (host->version < SDHCI_SPEC_300)
+        return 0;
+
+    switch (ios->signal_voltage) {
+    case MMC_SIGNAL_VOLTAGE_330:
+        if (!(host->flags & SDHCI_SIGNALING_330))
+            return -EINVAL;
+
+        ctrl &= ~SDHCI_CTRL_VDD_180;
+        sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+
+        if (!IS_ERR(mmc->supply.vqmmc)) {
+            ret = mmc_regulator_set_vqmmc(mmc, ios);
+            if (ret < 0) {
+                pr_warn("%s: Switching to 3.3V signalling voltage failed\n",
+                    mmc_hostname(mmc));
+                return -EIO;
+            }
+        }
+
+        usleep_range(5000, 5500);
+
+        ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+        if (!(ctrl & SDHCI_CTRL_VDD_180))
+            return 0;
+
+        pr_warn("%s: 3.3V regulator output did not become stable\n",
+            mmc_hostname(mmc));
+
+        return -EAGAIN;
+
+    case MMC_SIGNAL_VOLTAGE_180:
+        if (!(host->flags & SDHCI_SIGNALING_180))
+            return -EINVAL;
+
+        if (!IS_ERR(mmc->supply.vqmmc)) {
+            ret = mmc_regulator_set_vqmmc(mmc, ios);
+            if (ret < 0) {
+                pr_warn("%s: Switching to 1.8V signalling voltage failed\n",
+                    mmc_hostname(mmc));
+                return -EIO;
+            }
+        }
+
+        if (sdhci_am654->quirks & SDHCI_AM654_QUIRK_SET_V1P8_ENA) {
+            ctrl |= SDHCI_CTRL_VDD_180;
+            sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+
+            ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+            if (ctrl & SDHCI_CTRL_VDD_180)
+                return 0;
+
+            pr_warn("%s: 1.8V regulator output did not become stable\n",
+                mmc_hostname(mmc));
+
+            return -EAGAIN;
+        }
+        return 0;
+
+    default:
+        return 0;
+    }
+}
+
   static u8 sdhci_am654_write_power_on(struct sdhci_host *host, u8 val, int reg)
   {
       writeb(val, host->ioaddr + reg);
@@ -801,6 +875,8 @@ static int sdhci_am654_get_of_property(struct platform_device *pdev,
                       struct sdhci_am654_data *sdhci_am654)
   {
       struct device *dev = &pdev->dev;
+    struct device_node *np = dev->of_node;
+    struct device_node *node;
       int drv_strength;
       int ret;
   @@ -844,6 +920,15 @@ static int sdhci_am654_get_of_property(struct platform_device *pdev,
       if (device_property_read_bool(dev, "ti,fails-without-test-cd"))
           sdhci_am654->quirks |= SDHCI_AM654_QUIRK_FORCE_CDTEST;
   +    node = of_parse_phandle(np, "vmmc-supply", 0);
+
+    if (node) {
+        node = of_parse_phandle(np, "vqmmc-supply", 0);
+
+        if (!node)
+            sdhci_am654->quirks |= SDHCI_AM654_QUIRK_SET_V1P8_ENA;
+    }

It would be simpler without 'np' and 'node'.  Not sure
what the rule is meant to be, but it could be something like:

     if (of_parse_phandle(dev->of_node, "vmmc-supply", 0) &&
         of_parse_phandle(dev->of_node, "vqmmc-supply", 0)
         sdhci_am654->quirks |= SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA;

My issue with this is that I also need the quirk (SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA) for eMMC. DT node for eMMC does
not include vmmc and vqmmc supplies. That is why I had the quirk logic
inverted.

Ideally there would be a more direct way to distinguish eMMC, but
otherwise, having both supplies or neither would be:

	if (!!of_parse_phandle(dev->of_node, "vmmc-supply", 0) ==
	    !!of_parse_phandle(dev->of_node, "vqmmc-supply", 0))
		sdhci_am654->quirks |= SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA;


Not sure I love the double NOT, but ok, I can use this, will fix for v2.

Thanks for your suggestion!

~ Judith




This patch fixes timing issues with both eMMC and SD. (:

~ Judith



+
       sdhci_get_of_property(pdev);
         return 0;
@@ -940,6 +1025,7 @@ static int sdhci_am654_probe(struct platform_device *pdev)
           goto err_pltfm_free;
       }
   +    host->mmc_host_ops.start_signal_voltage_switch = sdhci_am654_start_signal_voltage_switch;
       host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
         pm_runtime_get_noresume(dev);

base-commit: cf6444ba528f043398b112ac36e041a4d8685cb1









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