2020-08-14 15:23:05

by Konrad Dybcio

Subject: [PATCH 1/2] [-next] mmc: host: msm: Add optional full power cycle property.

On some eMMCs (at least the ones used on Sony msm8994 boards)
enabling full power cycle is required to prevent permanent damage
to the flash memory, whereas on others it results in better performance.

Signed-off-by: Konrad Dybcio <[email protected]>
---
Documentation/devicetree/bindings/mmc/sdhci-msm.txt | 4 ++++
drivers/mmc/host/sdhci-msm.c | 6 ++++++
2 files changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
index 3b602fd6180b..939c8df2a25c 100644
--- a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
+++ b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
@@ -54,6 +54,10 @@ Required properties:
- qcom,dll-config: Chipset and Platform specific value. Use this field to
specify the DLL_CONFIG register value as per Hardware Programming Guide.

+- qcom,full-pwr-cycle: Enable full power cycle CAP2. This is required for optimal
+ performance on some eMMCs, whereas others need it to prevent permanent
+ damage to the flash memory.
+
Optional Properties:
* Following bus parameters are required for interconnect bandwidth scaling:
- interconnects: Pairs of phandles and interconnect provider specifier
diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
index 5a33389037cd..8d5c65e13dca 100644
--- a/drivers/mmc/host/sdhci-msm.c
+++ b/drivers/mmc/host/sdhci-msm.c
@@ -2242,6 +2242,12 @@ static int sdhci_msm_probe(struct platform_device *pdev)

msm_host->saved_tuning_phase = INVALID_TUNING_PHASE;

+ if (of_find_property(pdev->dev.of_node, "qcom,full-pwr-cycle", NULL))
+ msm_host->mmc->caps2 |= MMC_CAP2_FULL_PWR_CYCLE;
+
+ else
+ dev_info(&pdev->dev, "MMC full power cycle is not enabled. This might result in subpar performance or permanent damage on some devices.\n");
+
/* Setup SDCC bus voter clock. */
msm_host->bus_clk = devm_clk_get(&pdev->dev, "bus");
if (!IS_ERR(msm_host->bus_clk)) {
--
2.28.0

2020-08-14 15:24:59

by Konrad Dybcio

Subject: [PATCH 2/2] [-next] arm64: dts: qcom: kitakami: Enable qcom,full-pwr-cycle on SDHCI1

This is required to prevent permanent eMMC damage.

Signed-off-by: Konrad Dybcio <[email protected]>
---
arch/arm64/boot/dts/qcom/msm8994-sony-xperia-kitakami.dtsi | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/msm8994-sony-xperia-kitakami.dtsi b/arch/arm64/boot/dts/qcom/msm8994-sony-xperia-kitakami.dtsi
index 30cb3aa7d734..eb806d1e4454 100644
--- a/arch/arm64/boot/dts/qcom/msm8994-sony-xperia-kitakami.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8994-sony-xperia-kitakami.dtsi
@@ -439,6 +439,8 @@ &sdhc1 {
* vmmc-supply = <&pm8994_l20>;
* vqmmc-supply = <&pm8994_s4>;
*/
+
+ qcom,full-pwr-cycle;
};

&sdhc2 {
--
2.28.0

2020-08-14 22:46:49

by Konrad Dybcio

Subject: Re: [PATCH 1/2] [-next] mmc: host: msm: Add optional full power cycle property.

As I mentioned in the next email, please ignore this patch. The whole
idea is incorrect and does not solve the problem.

Konrad