Re: mmc_spi.c driver

From: Pierre Ossman <drzeus-mmc-p3sGCRWkH8CeZLLa646FqQ@public.gmane.org>
To: "hartleys" <hartleys-3FF4nKcrg1dE2c76skzGb0EOCMrvLtNR@public.gmane.org>
Cc: David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>,
	spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: Re: mmc_spi.c driver
Date: Thu, 24 Apr 2008 14:05:41 +0200	[thread overview]
Message-ID: <20080424140541.773f6e6b@mjolnir.drzeus.cx> (raw)
In-Reply-To: <1CF6EDDF0820924DA43C9A52FE7325950A89DA47-3jZfQB9DylyX6QUl2nWcdlaTQe2KTcn/@public.gmane.org>

On Tue, 15 Apr 2008 15:26:54 -0400
"hartleys" <hartleys@visionengravers.com> wrote:

> I do get the IRQ on every card insertion and removal. Actually if I boot
> the system with the card removed I end up getting a:
> 
> mmc0: error -22 whilst initialising SDIO card  

This is a bit odd. It shouldn't have gone down that route unless it is
sure it's an SDIO card it is dealing with.

> If I then insert the card I get the IRQ and:
> 
> mmc0: new MMC card on SPI
> mmcblk0: mmc0:0001 SDM064 62720KiB
>  mmcblk0: p1 p2 p3 p4
> 
> So it appears the initial card detect does work. But for some reason
> it's not seeing the removal of the card or the insertion of a new card.
> 
> Any ideas?  

Without debugging info it's impossible to tell if it's the driver or the core that's doing something wrong. Have you checked that interrupts keep coming?

> 
> New issue. All of my testing so far has been with MMC cards. All of them
> have worked so far. I just tried a couple of SD cards and none of them
> work with the driver, they do work fine on my host system.
> 
> One of the cards actually produces a "Division by zero in kernel." error.
> It appears to happen in the mmc_set_data_timeout() function. I added a
> printk to the function and get the following when the card is inserted.
> 
> mmc_set_data_timeout  timeout_ns:0  timeout_clks:0  ios.clock:400000
> mmc_set_data_timeout  timeout_ns:-589934592  timeout_clks:0  ios.clock:400000
> mmc0: new SD card on SPI
> mmcblk0: mmc0:0000       29888KiB
>  mmcblk0:mmc_set_data_timeout  timeout_ns:-589934592  timeout_clks:0  ios.clock:0
> Division by zero in kernel.

Ouch.

> 
> For some reason the card->host->ios.clock value is getting changed to 0 on
> the third call to the function. I haven't been able to trace down where/why
> this would happen. Any idea on that one?
> 

Not the slightest. It should never be set to zero except when powering
down, which it only does when there is no card attached.

> I didn't think of checking dmesg before, here's the actual dump after I
> insert
> the SD card:

My guess would be transfer problems that causes the core to believe the
card cannot handle a higher speed. We should of course have a check
that we don't compute a too low speed, but that's not the root of the
problem.

Have you disabled the CRC checks?

I guess I'll have to warm up my old SPI test board and get it updated.
David, I don't suppose you've checked if you can reproduce this?

Rgds
-- 
     -- Pierre Ossman

  Linux kernel, MMC maintainer        http://www.kernel.org
  PulseAudio, core developer          http://pulseaudio.org
  rdesktop, core developer          http://www.rdesktop.org

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