From: Philip Rakity <prakity@marvell.com>
To: Chris Ball <cjb@laptop.org>
Cc: "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
Albert Herranz <albert_herranz@yahoo.es>
Subject: Re: [BUG] CMD52 sent as first command not CMD0
Date: Sat, 5 Feb 2011 16:52:12 -0800 [thread overview]
Message-ID: <BC6C6C10-631A-4482-BA1B-C6F0057BC54A@marvell.com> (raw)
In-Reply-To: <20110206003845.GA15019@void.printf.net>
nothing negative but reset is meant to reinit the card. This is the power up sequence for the 1st time a card is detected.
There is no reason to do this if no card has yet enumerated. If a sdio card was there I completely agree with the mod since we need to reset
the card.
CMD0 should be the 1st command on an initial power up sequence. Does my code suggestion work for you ?
On Feb 5, 2011, at 4:38 PM, Chris Ball wrote:
> Hi Philip,
>
> On Fri, Feb 04, 2011 at 02:53:59PM -0800, Philip Rakity wrote:
>> using mmc-next -- NO changes -- last checkin was from linux Jan 26
> [..]
>> [ 2.034998] mmc0: starting CMD52 arg 00000c00 flags 00000195
>> [ 2.052704] Waiting 15sec before mounting root device...
>> [ 2.068948] sdhci [sdhci_irq()]: *** mmc0 got interrupt: 0x00018000
>> [ 2.087707] mmc0: req done (CMD52): -110: 00000000 00000000 00000000 00000000
>> [ 2.109069] mmc0: starting CMD52 arg 80000c08 flags 00000195
>> [ 2.126291] sdhci [sdhci_irq()]: *** mmc0 got interrupt: 0x00018000
>> [ 2.145002] mmc0: req done (CMD52): -110: 00000000 00000000 00000000 00000000
>> [ 2.166321] mmc0: clock 400000Hz busmode 1 powermode 2 cs 1 Vdd 21 width 0 timing 0
>> [ 2.190178] mmc0: starting CMD0 arg 00000000 flags 000000c0
>> [ 2.206971] sdhci [sdhci_irq()]: *** mmc0 got interrupt: 0x00000001
>> [ 2.225689] mmc0: req done (CMD0): 0: 00000000 00000000 00000000 00000000
>
> This looks to be intentional, and dates back to:
>
> commit 516a82422209e078345d0ca54b16793d7bfd4782
> Author: Albert Herranz <albert_herranz@yahoo.es>
> Date: Wed Mar 10 15:20:37 2010 -0800
>
> sdio: recognize io card without powercycle
>
> SDIO Simplified Specification V2.00 states that it is strongly recommended
> that the host executes either a power reset or issues a CMD52 (I/O Reset)
> to re-initialize an I/O only card or the I/O portion of a combo card.
> Additionally, the CMD52 must be issued first because it cannot be issued
> after a CMD0.
>
> With this patch the Nintendo Wii SDIO-based WLAN card is detected after a
> system reset, without requiring a complete system powercycle.
>
> Are you seeing any negative effects from running the CMD52 before CMD0?
>
> Thanks,
>
> --
> Chris Ball <cjb@laptop.org> <http://printf.net/>
> One Laptop Per Child
next prev parent reply other threads:[~2011-02-06 0:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-04 22:53 [BUG] CMD52 sent as first command not CMD0 Philip Rakity
2011-02-04 23:19 ` Philip Rakity
2011-02-06 0:38 ` Chris Ball
2011-02-06 0:52 ` Philip Rakity [this message]
2011-02-06 1:11 ` Philip Rakity
2011-02-06 1:15 ` Chris Ball
2011-02-06 1:35 ` Philip Rakity
2011-02-06 1:50 ` Chris Ball
2011-02-06 16:02 ` David Vrabel
2011-02-06 11:13 ` Albert Herranz
2011-02-06 20:50 ` Philip Rakity
2011-02-07 0:55 ` Nicolas Pitre
2011-02-06 16:09 ` Tardy, Pierre
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