[PATCH 1/2] dt-bindings: mmc: add no-mmc-hs400 flag

[PATCH 1/2] dt-bindings: mmc: add no-mmc-hs400 flag

[Lucas Stach]

HS400 requires a data strobe line in addition to the other MMC signal
lines, so if a board design neglects to wire up this signal, HS400 mode
is no available, even if both the controller and the eMMC are claiming
to support this mode. Add a DT flag to allow boards to disable the
HS400 support in this case.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
---
 Documentation/devicetree/bindings/mmc/mmc-controller.yaml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/mmc-controller.yaml b/Documentation/devicetree/bindings/mmc/mmc-controller.yaml
index e141330c1114..ac80d09df3a9 100644
--- a/Documentation/devicetree/bindings/mmc/mmc-controller.yaml
+++ b/Documentation/devicetree/bindings/mmc/mmc-controller.yaml
@@ -220,6 +220,11 @@ properties:
     description:
       eMMC HS400 enhanced strobe mode is supported
 
+  no-mmc-hs400:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description:
+      All eMMC HS400 modes are not supported.
+
   dsr:
     description:
       Value the card Driver Stage Register (DSR) should be programmed
-- 
2.31.1


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[PATCH 2/2] mmc: sdhci-esdhc-imx: add support for disabling HS400 mode via DT

[Lucas Stach]

On some boards the data strobe line isn't wired up, rendering HS400
support broken, even if both the controller and the eMMC claim to
support it. Allow to disable HS400 mode via DT.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
---
 drivers/mmc/host/sdhci-esdhc-imx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index a20459744d21..1d6068507fb6 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -1483,6 +1483,9 @@ sdhci_esdhc_imx_probe_dt(struct platform_device *pdev,
 	if (of_find_property(np, "no-1-8-v", NULL))
 		host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
 
+	if (of_find_property(np, "no-mmc-hs400", NULL))
+		host->quirks2 &= ~SDHCI_QUIRK2_CAPS_BIT63_FOR_HS400;
+
 	if (of_property_read_u32(np, "fsl,delay-line", &boarddata->delay_line))
 		boarddata->delay_line = 0;
 
-- 
2.31.1


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RE: [PATCH 2/2] mmc: sdhci-esdhc-imx: add support for disabling HS400 mode via DT

[Bough Chen]

[-- Attachment #1.1: Type: text/plain, Size: 1670 bytes --]

> -----Original Message-----
> From: Lucas Stach [mailto:dev@lynxeye.de]
> Sent: 2021年5月9日 4:57
> To: Rob Herring <robh+dt@kernel.org>; Ulf Hansson
<ulf.hansson@linaro.org>;
> Adrian Hunter <adrian.hunter@intel.com>
> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>; Fabio Estevam
> <festevam@gmail.com>; linux-mmc@vger.kernel.org;
> devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org
> Subject: [PATCH 2/2] mmc: sdhci-esdhc-imx: add support for disabling HS400
> mode via DT
> 
> On some boards the data strobe line isn't wired up, rendering HS400
support
> broken, even if both the controller and the eMMC claim to support it.
Allow to
> disable HS400 mode via DT.
> 
> Signed-off-by: Lucas Stach <dev@lynxeye.de>
> ---
>  drivers/mmc/host/sdhci-esdhc-imx.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c
> b/drivers/mmc/host/sdhci-esdhc-imx.c
> index a20459744d21..1d6068507fb6 100644
> --- a/drivers/mmc/host/sdhci-esdhc-imx.c
> +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
> @@ -1483,6 +1483,9 @@ sdhci_esdhc_imx_probe_dt(struct platform_device
> *pdev,
>  	if (of_find_property(np, "no-1-8-v", NULL))
>  		host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;
> 
> +	if (of_find_property(np, "no-mmc-hs400", NULL))
> +		host->quirks2 &= ~SDHCI_QUIRK2_CAPS_BIT63_FOR_HS400;
> +

Hi Lucas

I suggest you move the change to mmc_of_parse() in drivers/mmc/core/host.c
You also need to take care of the HS400ES mode.

Regards
Haibo Chen


>  	if (of_property_read_u32(np, "fsl,delay-line",
&boarddata->delay_line))
>  		boarddata->delay_line = 0;
> 
> --
> 2.31.1


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Re: [PATCH 1/2] dt-bindings: mmc: add no-mmc-hs400 flag

[Rob Herring]

On Sat, 08 May 2021 22:56:57 +0200, Lucas Stach wrote:
> HS400 requires a data strobe line in addition to the other MMC signal
> lines, so if a board design neglects to wire up this signal, HS400 mode
> is no available, even if both the controller and the eMMC are claiming
> to support this mode. Add a DT flag to allow boards to disable the
> HS400 support in this case.
> 
> Signed-off-by: Lucas Stach <dev@lynxeye.de>
> ---
>  Documentation/devicetree/bindings/mmc/mmc-controller.yaml | 5 +++++
>  1 file changed, 5 insertions(+)
> 

Acked-by: Rob Herring <robh@kernel.org>

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