linux-kernel - Re: [PATCH v2] mmc: sdhci: add quirk for broken write protect detection

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Date:	Thu, 20 Mar 2014 14:39:27 +0200
From:	Eli Billauer <eli.billauer@...il.com>
To:	monstr@...str.eu
Cc:	Sören Brinkmann <soren.brinkmann@...inx.com>,
	Mike Looijmans <mike.looijmans@...ic.nl>, chris@...ntf.net,
	michal.simek@...inx.com, linux-mmc@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mmc: sdhci: add quirk for broken write protect detection

Hello Michal.

The Zybo board doesn't have any WP pin connected to the MicroSD card. 
There is no physical possibility for the processor to know whether the 
card is write-protected or not.

As I mentioned earlier, the practical problem can be worked around by 
inverting the polarity of the WP bit, using wp-inverted. Practically 
speaking, there's no need for this patch.

I insisted on this patch, because I think that the device tree should 
reflect the hardware as it is, and not contain tricks for fooling the 
driver into doing what we want. But I guess this wasn't a reason good 
enough for adding yet another quirk (to the existing 38 or so).

Regards,
    Eli

On 20/03/14 14:26, Michal Simek wrote:
> we have got this from Mike (we couldn't reply because he has lost this email
> thread.
>
> Mike:
> "I think I found the issue. In ps7_init.c as generated by the tools, it sets the "WP" pin not to EMIO, but to MIO 0. We use pin 0 for a status LED.
>
> # devmem 0XF8000830
> 0x002E0000
>
> Register 0XF8000830 is SD0_WP_CD_SEL, and 0x002E0000 sets CD to pin 46 and WP to pin "0", not to EMIO as I specified in the design.
> "
>
> Eli: Maybe you have the same issue as Mike. Can you please check it?
>    

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