Re: [PATCH 0/2] Fix V1P8_SIGNAL_ENA and HIGH_SPEED_ENA

Hiago De Franco
2025-04-11T19:48:19Z

On Fri, Apr 11, 2025 at 11:37:14AM -0500, Judith Mendez wrote:
>
> The reason that patches fixes SD init for you is because in original patch,
> quirk was applied for both SD and eMMC with the exception of SD for am64x
> SoC. This patch only applies the quirk for eMMC.
>
> We cannot use the original implementation because the logic applying the
> quirk is based off of vmmc/vqmmc nodes in DT. The assumption was that am64x
> based boards will only have vmmc node since there is an internal LDO that is
> used to switch IO signal voltage instead of vqmmc. However, SolidRun
> HimmingBoard-T board has a different implementation on voltage regulator
> nodes in DT and the quirk applied to them as well and breaks their SD boot.
> So we now only apply the quirk for eMMC. Without this quirk applied to SD,
> am62x SD will continue having some stability issues.
>
> ~ Judith

I got the idea now, thanks for the explanation, I missed in the original
patches this was only about the eMMC and *not* the SD card. Is there any
plans to send patches to the SD card as well?

About that, I was wondering if instead of checking the bus_width to
apply the fix for the eMMC, we could set a devicetree property to
explicity apply the quirk. This way, we could also decide to apply it on
the SD node without checking any bus width. As example:

diff --git a/arch/arm64/boot/dts/ti/k3-am62-verdin.dtsi b/arch/arm64/boot/dts/ti/k3-am62-verdin.dtsi
index 1ea8f64b1b3b..c4423c09e809 100644
--- a/arch/arm64/boot/dts/ti/k3-am62-verdin.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-am62-verdin.dtsi
@@ -1466,6 +1466,7 @@ &sdhci1 {
vmmc-supply = <&reg_sdhc1_vmmc>;
vqmmc-supply = <&reg_sdhc1_vqmmc>;
ti,fails-without-test-cd;
+ ti,suppress-v1p8-ena;
status = "disabled";
};

diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
index 4e1156a2f1b8..a0485c2bb549 100644
--- a/drivers/mmc/host/sdhci_am654.c
+++ b/drivers/mmc/host/sdhci_am654.c
@@ -87,7 +87,6 @@
#define CLOCK_TOO_SLOW_HZ 50000000
#define SDHCI_AM654_AUTOSUSPEND_DELAY -1
#define RETRY_TUNING_MAX 10
-#define BUS_WIDTH_8 8

/* Command Queue Host Controller Interface Base address */
#define SDHCI_AM654_CQE_BASE_ADDR 0x200
@@ -844,7 +843,6 @@ static int sdhci_am654_get_of_property(struct platform_device *pdev,
struct device *dev = &pdev->dev;
int drv_strength;
int ret;
- u32 bus_width;

if (sdhci_am654->flags & DLL_PRESENT) {
ret = device_property_read_u32(dev, "ti,trm-icp",
@@ -886,9 +884,11 @@ 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;

- /* Suppress V1P8_SIGNAL_ENA for eMMC */
- device_property_read_u32(dev, "bus-width", &bus_width);
- if (bus_width == BUS_WIDTH_8)
+ /*
+ * Suppress V1P8_SIGNAL_ENA for MMC devices if ti,suppress-v1p8-ena
+ * flag is present.
+ */
+ if (device_property_read_bool(dev, "ti,suppress-v1p8-ena"))
sdhci_am654->quirks |= SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA;

sdhci_get_of_property(pdev);

Which makes our Kingston SD card work again:

root@verdin-am62-15412807:~# dmesg | grep -i mmc1
[ 1.897055] mmc1: CQHCI version 5.10
[ 2.043673] mmc1: SDHCI controller on fa00000.mmc [fa00000.mmc] using ADMA 64-bit
[ 2.260610] mmc1: new UHS-I speed SDR104 SDHC card at address 0001
[ 2.268150] mmcblk1: mmc1:0001 SD32G 29.1 GiB

Sorry if I missed something, would also be a valid solution?

Cheers,
Hiago.