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SubjectRe: [PATCH] regulator: s2mps11: Fix invalid minimal selector for buck9 supplying SD card
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Hello Krzysztof,

On 03/27/2016 08:54 PM, Krzysztof Kozlowski wrote:
> The buck9 regulator of S2MPS11 PMIC lacked minimal selector for linear
> mapping. The mapping starts from 0x40 (3 V).
>

This patch is a real fix since the the SD error goes away and the regulator
driver probes correctly now.

> This buck9 provides power to other regulators, including LDO13 and LDO19
> which supply the MMC2 (SD card).
>

I think it's worth mentioning that this is the case for the Exynos5422 Odroid
XU{3,4} boards. I mean, the regulators can be used for anything but are those
boards that use LDO19 as the SD card supply.

In fact, I wonder if the subject line shouldn't be changed to something like:

"regulator: s2mps11: Fix invalid min selector and voltages num for buck9"

since the real problem is that the .linear_min_sel and .n_voltages are wrong.
The fact that the SD was failing on Odroids is just a consequence of that
(although I agree that this information should be part of the commit message).

> 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@vger.kernel.org>
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.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/drivers/regulator/s2mps11.c b/drivers/regulator/s2mps11.c
> index d24e2c783dc5..caeefc38ac47 100644
> --- a/drivers/regulator/s2mps11.c
> +++ b/drivers/regulator/s2mps11.c
> @@ -324,6 +324,23 @@ static struct regulator_ops s2mps11_buck_ops = {
> .enable_mask = S2MPS11_ENABLE_MASK \
> }
>
> +#define regulator_desc_s2mps11_buck9 { \
> + .name = "BUCK9", \
> + .id = S2MPS11_BUCK9, \
> + .ops = &s2mps11_buck_ops, \
> + .type = REGULATOR_VOLTAGE, \
> + .owner = THIS_MODULE, \
> + .min_uV = MIN_3000_MV, \
> + .uV_step = STEP_25_MV, \
> + .linear_min_sel = S2MPS11_BUCK9_MIN_VSEL, \

I don't have a datasheet for this PMIC but I wonder if buck9 is the only
buck regulator whose minimal register value is != 0. If that's not the
case, it would be good to fix the descriptions for all other regulators.

> + .n_voltages = S2MPS11_BUCK9_N_VOLTAGES, \
> + .ramp_delay = S2MPS11_RAMP_DELAY, \
> + .vsel_reg = S2MPS11_REG_B9CTRL2, \
> + .vsel_mask = S2MPS11_BUCK_VSEL_MASK, \
> + .enable_reg = S2MPS11_REG_B9CTRL1, \
> + .enable_mask = S2MPS11_ENABLE_MASK \
> +}
> +
> static const struct regulator_desc s2mps11_regulators[] = {
> regulator_desc_s2mps11_ldo(1, STEP_25_MV),
> regulator_desc_s2mps11_ldo(2, STEP_50_MV),
> @@ -371,7 +388,7 @@ static const struct regulator_desc s2mps11_regulators[] = {
> regulator_desc_s2mps11_buck6_10(6, MIN_600_MV, STEP_6_25_MV),
> regulator_desc_s2mps11_buck6_10(7, MIN_600_MV, STEP_6_25_MV),
> regulator_desc_s2mps11_buck6_10(8, MIN_600_MV, STEP_6_25_MV),
> - regulator_desc_s2mps11_buck6_10(9, MIN_3000_MV, STEP_25_MV),

Maybe the regulator_desc_s2mps11_buck6_10() define should be renamed?
Since it's no longer true that can be used for buck6-10, so the name
is misleading now.

Patch looks good to me though and as I said it fixes the issue so:

Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>

Best regards,
--
Javier Martinez Canillas
Open Source Group
Samsung Research America

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