linux-kernel - Re: [PATCH v4] mmc: Make ID freq configurable

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Date:	Thu, 2 Dec 2010 23:38:12 +0100
From:	Michal Miroslaw <mirq-linux@...e.qmqm.pl>
To:	Hein_Tibosch <hein_tibosch@...oo.es>,
	Sahitya Tummala <stummala@...eaurora.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Pierre Ossman <pierre@...man.eu>, Chris Ball <cjb@...top.org>,
	Ben Nizette <bn@...sdigital.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Adrian Hunter <adrian.hunter@...ia.com>,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Matt Fleming <matt@...sole-pimps.org>
Subject: Re: [PATCH v4] mmc: Make ID freq configurable

On Fri, Dec 03, 2010 at 05:21:10AM +0800, Hein_Tibosch wrote:
> Hi Sahitya,
> On 2-12-2010 19:16, Sahitya Tummala wrote:
> > Hi Hein Tibosch,
> >
> > On Fri, 2010-09-03 at 05:34 +0800, Hein_Tibosch wrote:
> >> In the latest releases of the mmc driver, the freq during initialization
> >> is set to a fixed 400 Khz. This was reportedly too fast for several
> >> users. As there doesn't seem to be an ideal frequency which-works-for-all,
> >> Pierre suggested to let the driver try several frequencies.
> >> <cut>
> >> +		/*
> >> +		 * First we search for SDIO...
> >> +		 */
> >> +		err = mmc_send_io_op_cond(host, 0, &ocr);
> >> +		if (!err) {
> >> +			if (mmc_attach_sdio(host, ocr)) {
> >> +				mmc_claim_host(host);
> >> +				/* try SDMEM (but not MMC) even if SDIO is broken */
> >> +				if (mmc_send_app_op_cond(host, 0, &ocr))
> > In case of SDIO error, mmc_power_off() is getting called as part of
> > mmc_detach_bus().  Shouldn't we power up the host before checking for
> > SDMEM? Any comments?
> I think you should ask Michal Miroslaw, as he wrote the patch for the
> SD-combo (IO + mem)*
> 
> But yes, in case of a failure, mmc_attach_sdio() will call mmc_detach_bus()
> which in turn will call mmc_power_off()
> 
> And so it should be mmc_power_up() again before trying to detect SD memory.

Yes, you are right!  This explains some things...

Please try attached patch. (Not tested, but obvious enough.)

Best Regards,
Michał Mirosław

---

mmc: fix detection of memory part of SD-combo card with broken SDIO

In case of failure, mmc_attach_sdio() will power off the SD bus.
Power it up and reinitialize before trying SD memory detection.

Reported-by: Sahitya Tummala <stummala@...eaurora.org>
Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
---
 drivers/mmc/core/core.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 6286898..32a4798 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1564,6 +1564,11 @@ void mmc_rescan(struct work_struct *work)
 				 * Try SDMEM (but not MMC) even if SDIO
 				 * is broken.
 				 */
+				mmc_power_up(host);
+				sdio_reset(host);
+				mmc_go_idle(host);
+				mmc_send_if_cond(host, host->ocr_avail);
+
 				if (mmc_send_app_op_cond(host, 0, &ocr))
 					goto out_fail;
 
-- 
1.7.2.3

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