From: Aaron Lu <aaron.lu@amd.com>
To: Girish K S <girish.shivananjappa@linaro.org>
Cc: Philip Rakity <prakity@marvell.com>,
"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
"linux-samsung-soc@vger.kernel.org"
<linux-samsung-soc@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: confusion regarding the CMD19 and CMD21 in eMMC/SD card spec
Date: Fri, 16 Sep 2011 12:47:08 +0800 [thread overview]
Message-ID: <20110916044706.GA4030@lovegaga> (raw)
In-Reply-To: <CAGxe1ZG4QjwB5OfrxupG_C+DtQ7sTQ4_EURaF-QrqPPSA3A0jw@mail.gmail.com>
On Fri, Sep 16, 2011 at 09:41:04AM +0530, Girish K S wrote:
> but there is only one host controller to handle these commands.
> the generic sdhci driver has cmd19 hard coded, thats the reason I
> asked the question.
> you can also check it in the function sdhci_execute_tuning it is hard coded as
> cmd.opcode = MMC_SEND_TUNING_BLOCK; where the macro value is 19.
> So in case of SD card insertion it will send a SEND_TUNING_BLOCK
> command to the device. but if
> MMC card is inserted then it will send a BUS_TEST_W command to the device.
sdhci_execute_tuning will only be called if the inserted card is a sd card
and it is operating at SDR104 or SDR50 mode(UHS-I).
The host's tuning function is called from the mmc_sd_init_uhs_card,
and for a mmc card, there is no chance of that function being called.
-Aaron
WARNING: multiple messages have this Message-ID (diff)
From: aaron.lu@amd.com (Aaron Lu)
To: linux-arm-kernel@lists.infradead.org
Subject: confusion regarding the CMD19 and CMD21 in eMMC/SD card spec
Date: Fri, 16 Sep 2011 12:47:08 +0800 [thread overview]
Message-ID: <20110916044706.GA4030@lovegaga> (raw)
In-Reply-To: <CAGxe1ZG4QjwB5OfrxupG_C+DtQ7sTQ4_EURaF-QrqPPSA3A0jw@mail.gmail.com>
On Fri, Sep 16, 2011 at 09:41:04AM +0530, Girish K S wrote:
> but there is only one host controller to handle these commands.
> the generic sdhci driver has cmd19 hard coded, thats the reason I
> asked the question.
> you can also check it in the function sdhci_execute_tuning it is hard coded as
> cmd.opcode = MMC_SEND_TUNING_BLOCK; where the macro value is 19.
> So in case of SD card insertion it will send a SEND_TUNING_BLOCK
> command to the device. but if
> MMC card is inserted then it will send a BUS_TEST_W command to the device.
sdhci_execute_tuning will only be called if the inserted card is a sd card
and it is operating at SDR104 or SDR50 mode(UHS-I).
The host's tuning function is called from the mmc_sd_init_uhs_card,
and for a mmc card, there is no chance of that function being called.
-Aaron
next prev parent reply other threads:[~2011-09-16 4:47 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-15 11:58 confusion regarding the CMD19 and CMD21 in eMMC/SD card spec Girish K S
2011-09-15 11:58 ` Girish K S
2011-09-15 16:23 ` Philip Rakity
2011-09-15 16:23 ` Philip Rakity
2011-09-16 4:11 ` Girish K S
2011-09-16 4:11 ` Girish K S
2011-09-16 4:47 ` Aaron Lu [this message]
2011-09-16 4:47 ` Aaron Lu
2011-09-16 5:30 ` Girish K S
2011-09-16 5:30 ` Girish K S
2011-09-16 5:57 ` Aaron Lu
2011-09-16 5:57 ` Aaron Lu
2011-09-16 6:14 ` Girish K S
2011-09-16 6:14 ` Girish K S
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