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Date: Sun, 5 Sep 2010 21:43:36 +0100
From: Chris Ball <cjb@...top.org>
To: Matt Fleming <matt@...sole-pimps.org>
Cc: Hein_Tibosch <hein_tibosch@...oo.es>,
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
Subject: Re: [PATCH v4] mmc: Make ID freq configurable
Hi Matt,
On Sun, Sep 05, 2010 at 09:14:48PM +0100, Matt Fleming wrote:
> On Fri, Sep 03, 2010 at 05:34:53AM +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.
> >
> > This patch implements that idea. It will try mmc-initialization using
> > several frequencies from an array 400, 300, 200 and 100.
> > I submitted it earlier but it's now adapted to and tested with kernel
> > 2.6.36-rc3.
> >
> > In case SDIO is broken, it'll still try to detect SDMEM, also at different
> > freqs.
> >
> > Signed-off-by: Hein Tibosch <hein_tibosch@...oo.es>
> >
> > ---
> > diff -Nurp a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> > --- a/drivers/mmc/core/core.c 2010-08-29 23:36:04.000000000 +0800
> > +++ b/drivers/mmc/core/core.c 2010-09-03 04:28:52.000000000 +0800
> > @@ -907,12 +907,7 @@ static void mmc_power_up(struct mmc_host
> > */
> > mmc_delay(10);
> >
> > - if (host->f_min > 400000) {
> > - pr_warning("%s: Minimum clock frequency too high for "
> > - "identification mode\n", mmc_hostname(host));
> > - host->ios.clock = host->f_min;
> > - } else
> > - host->ios.clock = 400000;
> > + host->ios.clock = host->f_init;
> >
> > host->ios.power_mode = MMC_POWER_ON;
> > mmc_set_ios(host);
> > @@ -1404,6 +1399,8 @@ void mmc_rescan(struct work_struct *work
> > u32 ocr;
> > int err;
> > unsigned long flags;
> > + int i;
> > + unsigned freqs[] = { 400000, 300000, 200000, 100000 };
> >
> > spin_lock_irqsave(&host->lock, flags);
> >
> > @@ -1443,55 +1440,64 @@ void mmc_rescan(struct work_struct *work
> > if (host->ops->get_cd && host->ops->get_cd(host) == 0)
> > goto out;
> >
> > - mmc_claim_host(host);
> > + for (i = 0; i < ARRAY_SIZE(freqs); i++) {
> > + mmc_claim_host(host);
> >
> > - mmc_power_up(host);
> > - sdio_reset(host);
> > - mmc_go_idle(host);
> > + if (freqs[i] >= host->f_min)
> > + host->f_init = freqs[i];
> > + else if (i && freqs[i-1] <= host->f_min)
> > + goto out;
>
> The label 'out' does not release the claim on the host.
Thanks for catching that.
> > + else
> > + host->f_init = host->f_min;
> >
> > - mmc_send_if_cond(host, host->ocr_avail);
> > + printk ("mmc_rescan: trying %u Hz\n", host->f_init);
> > + mmc_power_up(host);
> > + sdio_reset(host);
> > + mmc_go_idle(host);
> >
> > - /*
> > - * 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))
> > - goto out_fail;
> > + mmc_send_if_cond(host, host->ocr_avail);
> > +
> > + /*
> > + * 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))
> > + goto out_fail;
> > +
> > + if (mmc_attach_sd(host, ocr))
> > + mmc_power_off(host);
> > + }
> > + goto out;
> > + }
> >
> > + /*
> > + * ...then normal SD...
> > + */
> > + err = mmc_send_app_op_cond(host, 0, &ocr);
> > + if (!err) {
> > if (mmc_attach_sd(host, ocr))
> > mmc_power_off(host);
> > + goto out;
>
> Same problem here.
>
> > }
> > - goto out;
> > - }
> >
> > - /*
> > - * ...then normal SD...
> > - */
> > - err = mmc_send_app_op_cond(host, 0, &ocr);
> > - if (!err) {
> > - if (mmc_attach_sd(host, ocr))
> > - mmc_power_off(host);
> > - goto out;
> > - }
> > -
> > - /*
> > - * ...and finally MMC.
> > - */
> > - err = mmc_send_op_cond(host, 0, &ocr);
> > - if (!err) {
> > - if (mmc_attach_mmc(host, ocr))
> > - mmc_power_off(host);
> > - goto out;
> > - }
> > + /*
> > + * ...and finally MMC.
> > + */
> > + err = mmc_send_op_cond(host, 0, &ocr);
> > + if (!err) {
> > + if (mmc_attach_mmc(host, ocr))
> > + mmc_power_off(host);
> > + goto out;
> > + }
>
> And here.
Actually, mmc_attach_{sd,mmc}() both do release the host as part of
their failure case, so I don't think there's a problem with these two.
- Chris.
--
Chris Ball <cjb@...top.org> <http://printf.net/>
One Laptop Per Child
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