From: Jaehoon Chung <jh80.chung@samsung.com>
To: Shawn Lin <shawn.lin@kernel-upstream.org>,
Shawn Lin <shawn.lin@rock-chips.com>,
linux-mmc@vger.kernel.org
Cc: ulf.hansson@linaro.org
Subject: Re: [PATCH 1/2] mmc: dw_mmc: retry to switch voltage when failed
Date: Wed, 11 May 2016 11:51:48 +0900 [thread overview]
Message-ID: <57329E44.6020905@samsung.com> (raw)
In-Reply-To: <cd8e28bf-1c4d-7502-60cb-382685d43f17@kernel-upstream.org>
On 05/10/2016 06:24 PM, Shawn Lin wrote:
> On 2016/5/10 9:55, Jaehoon Chung wrote:
>> Hi Shawn,
>>
>> On 05/04/2016 07:41 PM, Shawn Lin wrote:
>>> 在 2016/5/4 15:14, Jaehoon Chung 写道:
>>>> If vqmmc is used and failed to switch voltage, then retry to switch
>>>> voltage. MMC core is providing the retrying scheame.
>>>>
>>>> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
>>>> ---
>>>> drivers/mmc/host/dw_mmc.c | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>>>> index 9dd1bd3..28602cc 100644
>>>> --- a/drivers/mmc/host/dw_mmc.c
>>>> +++ b/drivers/mmc/host/dw_mmc.c
>>>> @@ -1416,7 +1416,7 @@ static int dw_mci_switch_voltage(struct mmc_host *mmc, struct mmc_ios *ios)
>>>> dev_dbg(&mmc->class_dev,
>>>> "Regulator set error %d - %s V\n",
>>>> ret, uhs & v18 ? "1.8" : "3.3");
>>>> - return ret;
>>>> + return -EAGAIN;
>>>> }
>>>> }
>>>
>>> If not vqmmc is assigned, dw_mci_switch_voltage still returns success to
>>> mmc core?
>>
>> There is comment in dw_mci_switch_voltage().. In some SoC, it's not harmful to switch voltage.
>> But we can decide this condition whether try to set both or not.
>
>
> Because for dw_mmc-rockchip, we always need to swicth voltage by
> regulator. So do you mean some exynos Socs can switch voltage just
> by setting UHS_REG!? So to make things safe, we can set UHS_REG and
> switch voltage by regulator both?
Ok. I will update the patch.
Best Regards,
Jaehoon Chung
>
>
>
>>
>> Best Regards,
>> Jaehoon Chung
>>
>>>
>>>> mci_writel(host, UHS_REG, uhs);
>>>>
>>>
>>>
>>
>> --
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>>
>
> --
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>
prev parent reply other threads:[~2016-05-11 2:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-04 7:14 [PATCH 1/2] mmc: dw_mmc: retry to switch voltage when failed Jaehoon Chung
2016-05-04 7:14 ` [PATCH 2/2] mmc: dw_mmc: prevent to set the wrong value Jaehoon Chung
2016-05-04 10:35 ` Shawn Lin
2016-05-10 1:49 ` Jaehoon Chung
2016-05-04 10:41 ` [PATCH 1/2] mmc: dw_mmc: retry to switch voltage when failed Shawn Lin
2016-05-10 1:55 ` Jaehoon Chung
2016-05-10 9:24 ` Shawn Lin
2016-05-11 2:51 ` Jaehoon Chung [this message]
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