Re: [PATCH v2] mmc: sdhci: add quirk for broken write protect detection
From: Mike Looijmans <hidden>
Date: 2014-03-06 13:41:20
Also in:
linux-mmc, lkml
On 03/04/2014 10:00 PM, Sören Brinkmann wrote:
On Tue, 2014-03-04 at 10:06PM +0200, Eli Billauer wrote:quoted
Hello Sören, wp-inverted solves the practical problem indeed, and fools the driver into thinking that the card has an inverted write protection sensor, and the logic zero that it finds in the hardware register means that the card isn't write protected. I'm insisting on this patch, because I think that the device tree should describe the hardware as it is, and not fool the driver into behaving the way we want it to. These tricks always bite back later on.Well, why is broken-wp more accurate than wp-inverted? Strictly speaking the WP is there and working, it's just tied off to some value you want to have interpreted the other way. Anyway, seems like this is solvable with wp-inverted and whether the additional quirk is needed I leave to others do decide.
I've begged for this patch - or a similar one - to be included too, because on our boards, the "wp" value appears to be sort of random. Out of 5 prototype boards, 3 would only boot with wp-inverted while the other 2 wouldn't boot with wp-inverted set. In our case I really don't know (and I don't care either) to which logic level the wp happens to think it's wired. I just want to be able to tell the driver that the WP line is free-floating-and-might-have-any-random-value-at-any-given-moment which is a bit long, so I'd go for disable-wp instead. Mike. Met vriendelijke groet / kind regards, Mike Looijmans TOPIC Embedded Systems Eindhovenseweg 32-C, NL-5683 KH Best Postbus 440, NL-5680 AK Best Telefoon: (+31) (0) 499 33 69 79 Telefax: (+31) (0) 499 33 69 70 E-mail: mike.looijmans@topic.nl Website: www.topic.nl Please consider the environment before printing this e-mail