Re: [PATCH 2/2] ARM: dts: at91: sama5d27_som1_ek: add mmc capabilities for SDMMC0

On 09.08.2019 09:23, Ludovic Desroches wrote:

On Thu, Aug 08, 2019 at 03:57:30PM +0300, Adrian Hunter wrote:

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On 8/08/19 3:42 PM, Ludovic Desroches wrote:

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On Thu, Aug 08, 2019 at 10:35:43AM +0200, Eugen Hristev - M18282 wrote:

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From: Eugen Hristev <redacted>

Add mmc capabilities for SDMMC0 for this board.
With this enabled, eMMC connected card is detected as:

mmc0: new DDR MMC card at address 0001

Signed-off-by: Eugen Hristev <redacted>

Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>

I am interested to have the some insights about the use of sd-uhs-*
properties.

Our IP can't deal with 1V8 by itself. It has a 1V8SEL signal which can
be used as the logic control input of a mux. So even if the IP claims
to support UHS modes, it depends on the board.

Are the sd-uhs-* properties a way to deal with this? I tend to think no
as sdhci_setup_host() will set the caps depending on the content of the
capabilities register. Do we have to use the SDHCI_QUIRK_MISSING_CAPS
quirk or sdhci-caps/sdhci-caps-mask?

There is "no-1-8-v" which it looks like sdhci-of-at91.c already supports:

   sdhci_at91_probe() -> sdhci_get_of_property() -> sdhci_get_property()

     	if (device_property_present(dev, "no-1-8-v"))
		host->quirks2 |= SDHCI_QUIRK2_NO_1_8_V;

Right, I forgot this property. Thanks.

Eugen, do you see cases we can't cover with this property?

Hi,

For current requirements and driver support, this should be enough.

I noticed one thing regarding SD-Cards, if I add property sd-uhs-sdr104 
the class 10 uhs1 cards are detected as SDR104 . Without this property 
they are detected as DDR50. Any idea why the difference ? The controller 
does not claim to have SDR104 support ?  We should add it ?

Eugen

Regards

Ludovic

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Regards

Ludovic

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---
  arch/arm/boot/dts/at91-sama5d27_som1_ek.dts | 1 +
  1 file changed, 1 insertion(+)

diff --git a/arch/arm/boot/dts/at91-sama5d27_som1_ek.dts b/arch/arm/boot/dts/at91-sama5d27_som1_ek.dts
index 149e539..194b3a3 100644
--- a/arch/arm/boot/dts/at91-sama5d27_som1_ek.dts
+++ b/arch/arm/boot/dts/at91-sama5d27_som1_ek.dts

@@ -54,6 +54,7 @@
  
  		sdmmc0: sdio-host@a0000000 {
  			bus-width = <8>;
+			mmc-ddr-3_3v;
  			pinctrl-names = "default";
  			pinctrl-0 = <&pinctrl_sdmmc0_default>;
  			status = "okay";

-- 
2.7.4