From: Adrian Hunter <adrian.hunter@intel.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Ulf Hansson <ulf.hansson@stericsson.com>,
linux-mmc <linux-mmc@vger.kernel.org>,
Chris Ball <cjb@laptop.org>,
Johan Rudholm <johan.rudholm@stericsson.com>
Subject: Re: [PATCH 1/3] mmc: core: Remove power_restore bus_ops for mmc and sd
Date: Thu, 04 Apr 2013 15:00:02 +0300 [thread overview]
Message-ID: <515D6B42.1000005@intel.com> (raw)
In-Reply-To: <CAPDyKFq--WgU4XDtsdzU2DN36G0bHN+UGG6N8Q2p0Fue9XJqvQ@mail.gmail.com>
On 04/04/13 14:52, Ulf Hansson wrote:
> On 4 April 2013 13:44, Adrian Hunter <adrian.hunter@intel.com> wrote:
>> On 04/04/13 12:55, Ulf Hansson wrote:
>>> On 4 April 2013 10:46, Adrian Hunter <adrian.hunter@intel.com> wrote:
>>>> On 01/03/13 14:47, Ulf Hansson wrote:
>>>>> From: Ulf Hansson <ulf.hansson@linaro.org>
>>>>>
>>>>> The mmc_power_restore|save_host API is only used by SDIO func drivers. SDIO
>>>>
>>>> NAK - it is also used by eMMC hardware reset i.e. mmc_do_hw_reset()
>>>
>>> True for eMMC, but for SD card the bus_ops can go away. Thanks for
>>> spotting this Adrian!
>>>
>>> Although, I see some serious problems with the mmc_do_hw_reset
>>> function - it could cause eMMC data corruption.
>>>
>>> Issuing hw reset and doing re-initialization by using the mmc
>>> bus_ops->power_restore will mean no consideration is taken to "cache
>>> ctrl", "bkops" and "power off notify". I think it must.
>>>
>>> So the more proper way instead of calling power_restore, should be to
>>> use bus_ops->suspend and bus_ops->resume callbacks from the
>>> mmc_do_hw_reset function. Additionally if bus_ops->suspend is done
>>> successfully, we should be able to skip the actual hw reset and just
>>> do bus_ops->resume.
>>>
>>> Do you have any thoughts on this?
>>
>> Certainly the bootloader should leave the eMMC is a safe state including:
>> flushing the cache or turning it off (why did it turn on?), stopping
>> background operations (why did it start them?), disabling power-off
>> notification CMD0? (again why it it enable it?)
>
> Not sure what you mean here. What has a booloader to do with this?
When do you think hw reset is used?
>
>>
>> Note that according to spec. CMD0 anyway clears the cache so you have lost
>> your data anyway.
>
> What I am saying that we can try send "cache ctrl" and "power off
> notify" before we send CMD0 / do hw reset. The no data shall be lost.
With an uninitialized bus? Or an unresponsive card?
next prev parent reply other threads:[~2013-04-04 11:54 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-01 12:47 [PATCH 0/3] mmc: Use runtime pm for blkdevice Ulf Hansson
2013-03-01 12:47 ` [PATCH 1/3] mmc: core: Remove power_restore bus_ops for mmc and sd Ulf Hansson
2013-04-03 11:08 ` merez
2013-04-04 8:46 ` Adrian Hunter
2013-04-04 9:55 ` Ulf Hansson
2013-04-04 11:44 ` Adrian Hunter
2013-04-04 11:52 ` Ulf Hansson
2013-04-04 12:00 ` Adrian Hunter [this message]
2013-04-04 14:58 ` Ulf Hansson
2013-04-05 8:50 ` Adrian Hunter
2013-03-01 12:47 ` [PATCH 2/3] mmc: core: Add bus_ops for runtime pm callbacks Ulf Hansson
2013-04-03 11:49 ` merez
2013-03-01 12:47 ` [PATCH 3/3] mmc: block: Enable runtime pm for mmc blkdevice Ulf Hansson
2013-03-04 13:48 ` Asutosh Das
2013-03-05 1:39 ` Ulf Hansson
2013-03-05 18:04 ` Asutosh Das
2013-03-06 6:57 ` Ulf Hansson
2013-04-01 8:28 ` Asutosh Das
2013-04-02 10:38 ` Ulf Hansson
2013-04-02 12:37 ` Subhash Jadavani
2013-04-03 11:50 ` merez
2013-03-02 20:00 ` [PATCH 0/3] mmc: Use runtime pm for blkdevice Maya Erez
2013-03-27 13:31 ` Chris Ball
2013-03-27 13:40 ` Arnd Bergmann
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