From: Alim Akhtar <alim.akhtar@gmail.com>
To: Doug Anderson <dianders@chromium.org>
Cc: "Addy Ke" <addy.ke@rock-chips.com>,
"Jaehoon Chung" <jh80.chung@samsung.com>,
"Ulf Hansson" <ulf.hansson@linaro.org>,
"Olof Johansson" <olof@lixom.net>,
"Andrzej Hajda" <a.hajda@samsung.com>,
"Heiko Stübner" <heiko@sntech.de>,
"Eddie Cai" <cf@rock-chips.com>, lintao <lintao@rock-chips.com>,
"Tao Huang" <huangtao@rock-chips.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"open list:ARM/Rockchip SoC..."
<linux-rockchip@lists.infradead.org>,
"Javier Martinez Canillas" <javier.martinez@collabora.co.uk>
Subject: Re: [PATCH v4 1/3] mmc: dw_mmc: update clock after host reach a stable voltage
Date: Wed, 25 Feb 2015 13:22:36 +0530 [thread overview]
Message-ID: <CAGOxZ53vcz96mFbb9ez3GAjZBqEQqiss_TmU1y7EQeRGTVLQdg@mail.gmail.com> (raw)
In-Reply-To: <CAD=FV=V9aK-78GJ_eWkpZZdVT_5Zu8ehxg_o3NtnpD2wyRuh7Q@mail.gmail.com>
Hi Doug,
On Fri, Feb 20, 2015 at 5:19 AM, Doug Anderson <dianders@chromium.org> wrote:
> Alim and Addy,
>
> On Sun, Feb 15, 2015 at 3:28 PM, Alim Akhtar <alim.akhtar@gmail.com> wrote:
>> Hi Addy,
>>
>> On Sat, Feb 14, 2015 at 11:47 AM, Addy Ke <addy.ke@rock-chips.com> wrote:
>>> As show in mmc_power_up(), in MMC_POWER_UP state, the voltage isn't
>>> stable and we may get 'data busy' which can't be cleaned by resetting
>>> all blocks. So we should not send command to update clock in this state.
>>>
>>> Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
>>> ---
>>> drivers/mmc/host/dw_mmc.c | 3 ++-
>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>>> index 4d2e3c2..3472f9b 100644
>>> --- a/drivers/mmc/host/dw_mmc.c
>>> +++ b/drivers/mmc/host/dw_mmc.c
>>> @@ -1102,7 +1102,8 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>>> drv_data->set_ios(slot->host, ios);
>>>
>>> /* Slot specific timing and width adjustment */
>>> - dw_mci_setup_bus(slot, false);
>>> + if (ios->power_mode != MMC_POWER_UP)
>>> + dw_mci_setup_bus(slot, false);
>>>
>> This looks a HACK to me.
>> If stabilizing host voltage regulator is the problem, can you try out
>> below patch, and see if this resolve your issue?
>
> Actually, IMHO Alim's patch is more of a hack than Addy's. There's
> already a 10ms delay between "power up" and "power on" in the MMC core
> in mmc_power_up() state. That delay is commented as:
>
Well, my suggestion (adding 5ms in switch_volatge) was based on DW_MMC
databook (V2.41a) section "7.4.1.2 Voltage switch Normal Scenario"
step #7 which says:" After the 5ms timer expires, the host voltage
regulator is stable".
PS: I have limited to no access of my mails and workstation until
March 9th, so replies will be slow.
> /*
> * This delay should be sufficient to allow the power supply
> * to reach the minimum voltage.
> */
> mmc_delay(10);
>
> That means that assuming that the voltage is stable in MMC_POWER_UP is
> not valid anyway.
>
>
> Addy's patch certainly needs more comments. In another context Olof suggested:
>
> /*
> * Skip bus setup while voltage is still stabilizing. Instead,
> * bus setup will be done at MMC_POWER_ON.
> */
>
>
> ...thinking about this more, though: really the voltage should be
> stabilized when the regulator call returns (see my comments below).
> In actuality the "right" fix might be to just rearrange this function
> a little not to turn the clock on _before_ we even try to turn the
> voltage on.
>
> I've got that coded up but I'm still testing it... If you want to try
> it too, you can find it at
> <https://chromium-review.googlesource.com/251341>.
>
> Note that without my patch I find that I _really_ need Addy's patch to
> make sure that the card isn't busy in setup_bus. With my patch Addy's
> code catches the card busy less often. I'm still trying to see if
> there's a way to totally remove the need for his setup_bus and still
> trying to grok all the patches flying around...
>
>
>> ===========
>> [PATCH] mmc: dw_mmc: Wait for host voltage regulator to be stable
>>
>> Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
>> ---
>> drivers/mmc/host/dw_mmc.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index 4d2e3c2..dc10fbb 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -1202,6 +1202,9 @@ static int dw_mci_switch_voltage(struct mmc_host
>> *mmc, struct mmc_ios *ios)
>> }
>> mci_writel(host, UHS_REG, uhs);
>>
>> + /* wait for 5ms so that host voltage regulator is stable */
>> + usleep_range(5000, 5500);
>> +
>
> Alim: if you have some other instance where you actually need VQMMC to
> stabilize it should probably be done in a different way. If I
> understand correctly it is the regulator core's job to make sure that
> voltage is stable before returning. If you have a gpio-regulator you
> may be able to use "startup-delay-us" to specify how long the
> regulator takes to come up. You could also look at
> 'regulator-enable-ramp-delay'
>
> -Doug
--
Regards,
Alim
next prev parent reply other threads:[~2015-02-25 7:53 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-05 11:13 [PATCH] mmc: dw_mmc: fix bug that cause 'Timeout sending command' Addy Ke
2015-02-09 4:51 ` Ulf Hansson
2015-02-09 6:56 ` Addy
2015-02-09 7:04 ` Jaehoon Chung
2015-02-09 9:17 ` addy ke
2015-02-09 7:25 ` [PATCH v2 0/2] about data busy Addy Ke
2015-02-09 7:25 ` [PATCH v2 1/2] mmc: dw_mmc: fix bug that cause 'Timeout sending command' Addy Ke
2015-02-09 10:01 ` Jaehoon Chung
2015-02-11 3:07 ` Addy
2015-02-10 15:22 ` Alim Akhtar
2015-02-11 2:57 ` Addy
2015-02-11 11:58 ` Andrzej Hajda
2015-02-11 23:20 ` Alim Akhtar
2015-02-12 2:28 ` addy ke
2015-02-12 11:10 ` Andrzej Hajda
2015-02-12 13:59 ` Alim Akhtar
2015-02-13 8:15 ` addy ke
2015-02-12 11:13 ` Andrzej Hajda
2015-02-12 13:53 ` Alim Akhtar
2015-02-09 7:25 ` [PATCH v2 2/2] mmc: dw_mmc: Don't start command while data busy Addy Ke
2015-02-13 11:52 ` [PATCH v3 0/3] about " Addy Ke
2015-02-13 11:52 ` [PATCH v3 1/3] mmc: dw_mmc: update clock after host reach a stable voltage Addy Ke
2015-02-13 11:52 ` [PATCH v3 2/3] mmc: dw_mmc: fix bug that cause 'Timeout sending command' Addy Ke
2015-02-13 11:52 ` [PATCH v3 3/3] mmc: dw_mmc: Don't start command while data busy Addy Ke
2015-02-14 6:17 ` [PATCH v4 0/3] about " Addy Ke
2015-02-14 6:17 ` [PATCH v4 1/3] mmc: dw_mmc: update clock after host reach a stable voltage Addy Ke
2015-02-15 23:28 ` Alim Akhtar
2015-02-19 10:30 ` addy ke
2015-02-19 23:49 ` Doug Anderson
2015-02-20 0:02 ` Russell King - ARM Linux
2015-02-20 1:04 ` Doug Anderson
2015-02-20 19:05 ` Doug Anderson
2015-02-25 7:52 ` Alim Akhtar [this message]
2015-02-25 9:56 ` Jaehoon Chung
2015-02-25 21:05 ` Doug Anderson
2015-02-14 6:17 ` [PATCH v4 2/3] mmc: dw_mmc: fix bug that cause 'Timeout sending command' Addy Ke
2015-02-14 6:17 ` [PATCH v4 3/3] mmc: dw_mmc: Don't start command while data busy Addy Ke
2015-02-20 0:21 ` Doug Anderson
2015-02-15 11:41 ` [PATCH v4 0/3] about " Javier Martinez Canillas
2015-02-16 5:48 ` Jaehoon Chung
2015-02-16 11:09 ` Javier Martinez Canillas
2015-02-19 10:55 ` addy ke
2015-02-20 19:03 ` Doug Anderson
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