From: Russ Knize <Russ.Knize@motorola.com>
To: Andrei Warkentin <andreiw@motorola.com>
Cc: linux-mmc@vger.kernel.org
Subject: Re: [PATCH] mmc: power class support
Date: Mon, 4 Apr 2011 10:25:45 -0500 [thread overview]
Message-ID: <BANLkTikDc4+mT=jeM1WFt53-7mM3B-GRVA@mail.gmail.com> (raw)
In-Reply-To: <BANLkTi=x-6a5vtx3BHxifRBHEjimRApavQ@mail.gmail.com>
No, they were not switch timeouts. They were immediate failures due
to touchiness about init sequence. The card firmware was corrected
and the new samples don't have the issue. I don't think there are any
of these buggy ones in the wild, but I expect to see buggy firmware
coming from other vendors.
Russ W. Knize
Mobile Devices Android Platform
Desk: 847-523-9381
Mobile: 224-622-1391
On Sun, Apr 3, 2011 at 11:11 PM, Andrei Warkentin <andreiw@motorola.com> wrote:
> On Fri, Apr 1, 2011 at 7:28 PM, Andrei Warkentin <andreiw@motorola.com> wrote:
>> Hi Russ,
>>
>> On Fri, Apr 1, 2011 at 10:58 AM, Russ Knize <Russ.Knize@motorola.com> wrote:
>>> + /*
>>> + * Ignore switch errors from buggy cards that actually
>>> + * do switch successfully.
>>> + */
>>> + err = mmc_set_power_class(host, max_dtr, bus_width);
>>> + if (err && err != -EBADMSG)
>>> + goto free_card;
>>> +
>>
>> 1) host->card is not yet set at this moment, you probably want to pass
>> card to mmc_set_power_class as well .
>> 2) It seems like you will call mmc_set_power_class even if bus_width
>> == MMC_BUS_WIDTH_1. Is that supposed to work? 7.6.3 seems to imply
>> power classes only apply to 4-bit and 8-bit bus widths. As does the
>> paragraph on top of Page 138 of eMMC 4.41 spec, which says that for
>> 1-bit bus configuration the default applies (class 0).
>> 3) Since the current code supports DDR modes, you probably want to
>> extend support for PWR_CL_DDR_52_(360|195) as well.
>>
>> Just curious, for the cards reporting switch errors but nonetheless
>> switching to the power class, do they update the EXT_CSD field?
>>
>
> There was just a patch posted by Chuanxiao Dong ([PATCH v4 0/3]mmc:
> enable TRIM/ERASE caps for SDHCI host) against SDHCI core to enable
> setting proper timeout for R1B response-type commands, one of which is
> CMD6 (SWITCH). The patch is applicable to the kernel sources you've
> tested your patch on. Were the failures you've seen for cards erroring
> on MMC_SWITCH timeouts? Could you test with that change for the parts
> affected, and see if your problem in programming power level goes
> away?
>
> A
>
prev parent reply other threads:[~2011-04-04 15:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-01 15:58 [PATCH] mmc: power class support Russ Knize
2011-04-02 0:28 ` Andrei Warkentin
2011-04-02 0:44 ` Russ Knize
2011-04-04 4:11 ` Andrei Warkentin
2011-04-04 15:25 ` Russ Knize [this message]
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