linux-kernel - Re: [PATCH] regulator: s2mps11: Fix invalid minimal selector for buck9 supplying SD card

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Date:	Tue, 29 Mar 2016 10:08:56 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
Cc:	Sangbeom Kim <sbkim73@...sung.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org, linux-mmc@...r.kernel.org,
	Javier Martinez Canillas <javier@....samsung.com>,
	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
	stable@...r.kernel.org
Subject: Re: [PATCH] regulator: s2mps11: Fix invalid minimal selector for
 buck9 supplying SD card

On Mon, 28 Mar 2016, Krzysztof Kozlowski wrote:

> The buck9 regulator of S2MPS11 PMIC lacked minimal selector for linear
> mapping. The mapping starts from 0x40 (3 V).
> 
> This buck9 provides power to other regulators, including LDO13 and LDO19
> which supply the MMC2 (SD card).
> 
> Bootloader initializes the regulator with value of 0xff (5 V) which is
> outside of supported voltage range. When (during boot) constraints to
> buck9 were applied, the driver wrote value counting from 0x00, not 0x40.
> Effectively driver set lower voltage than required leading to SD card
> detection errors on Odroid XU3/XU4:
> 	mmc1: card never left busy state
> 	mmc1: error -110 whilst initialising SD card
> 
> Fixes: cb74685ecb39 ("regulator: s2mps11: Add samsung s2mps11 regulator driver")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> 
> ---
> 
> The issue can be reproduced on next-20160324 with
> bae4fdc88d7f7dda1 (regulator: core: Ensure we are at least in bounds
> for our constraints).
> ---
>  drivers/regulator/s2mps11.c         | 19 ++++++++++++++++++-
>  include/linux/mfd/samsung/s2mps11.h |  9 +++++++++
>  2 files changed, 27 insertions(+), 1 deletion(-)

[...]

> diff --git a/include/linux/mfd/samsung/s2mps11.h b/include/linux/mfd/samsung/s2mps11.h
> index b288965e8101..3937a932bfe0 100644
> --- a/include/linux/mfd/samsung/s2mps11.h
> +++ b/include/linux/mfd/samsung/s2mps11.h
> @@ -173,10 +173,19 @@ enum s2mps11_regulators {
>  
>  #define S2MPS11_LDO_VSEL_MASK	0x3F
>  #define S2MPS11_BUCK_VSEL_MASK	0xFF
> +#define S2MPS11_BUCK9_MIN_VSEL	0x40
>  #define S2MPS11_ENABLE_MASK	(0x03 << S2MPS11_ENABLE_SHIFT)
>  #define S2MPS11_ENABLE_SHIFT	0x06
>  #define S2MPS11_LDO_N_VOLTAGES	(S2MPS11_LDO_VSEL_MASK + 1)
>  #define S2MPS11_BUCK_N_VOLTAGES (S2MPS11_BUCK_VSEL_MASK + 1)
> +/*
> + * Buck9 supports only 32 voltages (values from 0x40 to 0x5F) but bootloader
> + * initializes the register with value of 0xff so when probing this would
> + * cause a failure (Odroid XU3):
> + *	vdd_2.8v_ldo: failed to get the current voltage(-22)
> + * Instead pretend we support up to 0xff (5 V).
> + */
> +#define S2MPS11_BUCK9_N_VOLTAGES	192

Err... NACK.

Please go and fix the bootloader instead of hacking the kernel.

>  #define S2MPS11_RAMP_DELAY	25000		/* uV/us */
>  
>  #define S2MPS11_CTRL1_PWRHOLD_MASK	BIT(4)

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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