On Fri, Sep 02, 2016 at 02:46:46PM +0200, Ulf Hansson wrote:
> On 2 September 2016 at 13:17, Simon Horman <horms+renesas@xxxxxxxxxxxx> wrote:
> > From: Ai Kyuse <ai.kyuse.uw@xxxxxxxxxxx>
> >
> > Add tuning support for use with SDR104 mode
> >
> > Signed-off-by: Ai Kyuse <ai.kyuse.uw@xxxxxxxxxxx>
> > Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
> > ---
> > v6 [Simon Horman]
> > * As suggested by Ulf Hansson:
> > - Restore saved tuning parameters on resume
> >
> > v5 [Simon Horman]
> > * As suggested by Ulf Hansson:
> > - Move hw reset support into a separate patch
> > - Use more descriptive name for callback to check for SSC error
> > - Rely on core to retune in case of -EILSEQ
> > - Document mandatory and optional callbacks
> >
> > v4 [Simon Horman]
> > * As suggested by Wolfram Sang:
> > - Do not perform tuning if host->select_tuning is not set:
> > it seems to make little sense to do so and moreover there is currently
> > no such use-case
> > - Do not add mrc->sbc handling from tmio_mmc_request,
> > this is a hang-over from earlier versions of this patchset which
> > did not use core infrastructure for retuning
> > - Tidy up local variable usage
> > * Correct index passed to prepare_tuning(): this seems to have
> > been the last piece of resolving the timeouts during tuning puzzle
> > * Further cleanups to tmio_mmc_execute_tuning():
> > - Ensure tap is sized proportionally to its members
> > - Remove stray '*' in comment
> > - Use mmc rather than host->mmc, these are equivalent but
> > the former seems tidier
> > - Correct inverted logic in setting tap values
> > * Re-introduce retuning support. This was removed in v3.
> >
> > v3 [Simon Horman]
> > * As suggested by Kuninori Morimoto:
> > - Do not add unused retuning callback to struct tmio_mmc_host
> > - Change return type of prepare_tuning callback to void
> > - Add tap_size parameter to select_tuning callback
> >
> > v2 [Simon Horman]
> > * As suggested by Kuninori Morimoto:
> > - Actually remove unnecessary TMIO_MMC_HAS_UHS_SCC define
> > * As suggested by Wolfram Sang:
> > - Rely on core to call tuning. This simplifies things somewhat.
> > - Use mmc_send_tuning()
> > - A side affect of this appears to be that we now see some recoverable
> > errors logged during tuning. These are typically corrected by
> > subsequent tuning. It is the logging that is the apparent side effect
> > of this change.
> > e.g.
> > sh_mobile_sdhi ee100000.sd: timeout waiting for hardware interrupt (CMD19)
> > sh_mobile_sdhi ee100000.sd: Tuning procedure failed
> > * Use bool rather than unsigned long to pass test status
> > to select_tuning() callback
> > * Do not retune if init_tuning callback is not present or
> > indicates that there are no taps present
> > * Retune on hardware reset
> >
> > v1 [Simon Horman]
> > * Omit start_signal_voltage_switch and tmio_mmc_card_busy changes which are
> > already present in mainline in a different form
> > * Return num from init_tuning rather than passing an extra parameter
> > to hold the return value
> > * Only call host->init_tuning if it is non-NULL
> > * Place tmio_mmc_execute_tuning() such that no new forward declarations are
> > required
> > * Remove unused TMIO_MMC_HAS_UHS_SCC define
> >
> > v0 [Ai Kyuse]
> > ---
> > drivers/mmc/host/tmio_mmc.h | 12 +++++++
> > drivers/mmc/host/tmio_mmc_pio.c | 69 +++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 81 insertions(+)
> >
> > diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
> > index 4b71f31fba63..4b501f2d529f 100644
> > --- a/drivers/mmc/host/tmio_mmc.h
> > +++ b/drivers/mmc/host/tmio_mmc.h
> > @@ -150,6 +150,7 @@ struct tmio_mmc_host {
> > struct mutex ios_lock; /* protect set_ios() context */
> > bool native_hotplug;
> > bool sdio_irq_enabled;
> > + u32 scc_tappos;
> >
> > /* Mandatory callback */
> > int (*clk_enable)(struct tmio_mmc_host *host);
> > @@ -165,6 +166,17 @@ struct tmio_mmc_host {
> > struct mmc_ios *ios);
> > int (*write16_hook)(struct tmio_mmc_host *host, int addr);
> > void (*hw_reset)(struct tmio_mmc_host *host);
> > + void (*prepare_tuning)(struct tmio_mmc_host *host, unsigned long tap);
> > + bool (*check_scc_error)(struct tmio_mmc_host *host);
> > +
> > + /* Mandatory callback for tuning to occur which is
> > + * optional for SDR50 and mandatory for SDR104 */
> > + unsigned int (*init_tuning)(struct tmio_mmc_host *host);
> > + int (*select_tuning)(struct tmio_mmc_host *host);
> > +
> > + /* Tuning values: 1 for success, 0 for failure */
> > + DECLARE_BITMAP(taps, BITS_PER_BYTE * sizeof(long));
> > + unsigned int tap_num;
> > };
> >
> > struct tmio_mmc_host *tmio_mmc_host_alloc(struct platform_device *pdev);
> > diff --git a/drivers/mmc/host/tmio_mmc_pio.c b/drivers/mmc/host/tmio_mmc_pio.c
> > index f1d36f4533d2..54aa14bb2f75 100644
> > --- a/drivers/mmc/host/tmio_mmc_pio.c
> > +++ b/drivers/mmc/host/tmio_mmc_pio.c
> > @@ -36,6 +36,7 @@
> > #include <linux/io.h>
> > #include <linux/irq.h>
> > #include <linux/mfd/tmio.h>
> > +#include <linux/mmc/card.h>
> > #include <linux/mmc/host.h>
> > #include <linux/mmc/mmc.h>
> > #include <linux/mmc/slot-gpio.h>
> > @@ -298,6 +299,11 @@ static void tmio_mmc_finish_request(struct tmio_mmc_host *host)
> > if (mrq->cmd->error || (mrq->data && mrq->data->error))
> > tmio_mmc_abort_dma(host);
> >
> > + if (host->check_scc_error && host->check_scc_error(host)) {
> > + mmc_retune_timer_stop(host->mmc);
> > + mmc_retune_needed(host->mmc);
>
> Instead of doing it like above, you should rather set cmd->error =
> -EILSEQ, which should trigger the mmc core to perform re-tuning in the
> request error path.
>
> I assume that's what you would like to happen, right!?
Ok, so something like this?
if (host->check_scc_error)
cmd->error = host->check_scc_error(host);
> > + }
> > +
> > mmc_request_done(host->mmc, mrq);
> > }
> >
> > @@ -764,6 +770,58 @@ static void tmio_mmc_hw_reset(struct mmc_host *mmc)
> > host->hw_reset(host);
> > }
> >
> > +static int tmio_mmc_execute_tuning(struct mmc_host *mmc, u32 opcode)
> > +{
> > + struct tmio_mmc_host *host = mmc_priv(mmc);
> > + int i, ret = 0;
> > +
> > + if (!host->tap_num) {
> > + if (!host->init_tuning || !host->select_tuning)
> > + /* Tuning is not supported */
> > + goto out;
> > +
> > + host->tap_num = host->init_tuning(host);
> > + if (!host->tap_num)
> > + /* Tuning is not supported */
> > + goto out;
> > + }
> > +
> > + if (host->tap_num * 2 >= sizeof(host->taps) * BITS_PER_BYTE) {
> > + dev_warn_once(&host->pdev->dev,
> > + "Too many taps, skipping tuning. Please consider "
> > + "updating size of taps field of tmio_mmc_host\n");
> > + goto out;
> > + }
> > +
> > + bitmap_zero(host->taps, host->tap_num * 2);
> > +
> > + /* Issue CMD19 twice for each tap */
> > + for (i = 0; i < 2 * host->tap_num; i++) {
> > + if (host->prepare_tuning)
> > + host->prepare_tuning(host, i % host->tap_num);
> > +
> > + ret = mmc_send_tuning(mmc, opcode, NULL);
> > + if (ret && ret != -EILSEQ)
> > + goto out;
> > + if (ret == 0)
> > + set_bit(i, host->taps);
> > +
> > + mdelay(1);
> > + }
> > +
> > + ret = host->select_tuning(host);
> > +
> > +out:
> > + if (ret < 0) {
> > + dev_warn(&host->pdev->dev, "Tuning procedure failed\n");
> > + mmc_hw_reset(mmc);
>
> Hmm. mmc_hw_reset() is supposed to be used to reset the *card* when we
> have encountered a hickup in the communication between the host and
> the card.
>
> Normally, the mmc core deals with error handling from a failed
> request, but I am trying to understand if there is something missing
> there as to be able to serve your needs?
>
> Perhaps what you need is only to reset the controller so it will be
> prepared for a new tuning sequence? Then you should do that without
> involving the core.
Previously tmio_mmc_hw_reset() was called which implicitly requested
retuning.
I think I should go back to calling tmio_mmc_hw_reset() here
assuming that the core will cause retuning to occur if an error
is returned (not so far below).
> > + } else {
> > + host->mmc->retune_period = 0;
>
> The retune period is default 0, so I am not sure you need this. If you
> want this explicitly to be set, let's do that in ->probe().
I'll see about removing the else clause.
> > + }
> > +
> > + return ret;
> > +}
> > +
> > /* Process requests from the MMC layer */
> > static void tmio_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
> > {
> > @@ -979,6 +1037,7 @@ static struct mmc_host_ops tmio_mmc_ops = {
> > .enable_sdio_irq = tmio_mmc_enable_sdio_irq,
> > .multi_io_quirk = tmio_multi_io_quirk,
> > .hw_reset = tmio_mmc_hw_reset,
> > + .execute_tuning = tmio_mmc_execute_tuning,
> > };
> >
> > static int tmio_mmc_init_ocr(struct tmio_mmc_host *host)
> > @@ -1216,6 +1275,11 @@ int tmio_mmc_host_runtime_suspend(struct device *dev)
> > }
> > EXPORT_SYMBOL(tmio_mmc_host_runtime_suspend);
> >
> > +static bool tmio_mmc_can_retune(struct tmio_mmc_host *host)
> > +{
> > + return host->tap_num && mmc_can_retune(host->mmc);
> > +}
> > +
> > int tmio_mmc_host_runtime_resume(struct device *dev)
> > {
> > struct mmc_host *mmc = dev_get_drvdata(dev);
> > @@ -1229,6 +1293,11 @@ int tmio_mmc_host_runtime_resume(struct device *dev)
> >
> > tmio_mmc_enable_dma(host, true);
> >
> > + if (tmio_mmc_can_retune(host) && host->select_tuning(host)) {
> > + dev_warn(&host->pdev->dev, "Tuning selection failed\n");
> > + mmc_hw_reset(mmc);
>
> This doesn't work, as mmc_hw_reset() requires you to keep the host claimed.
>
> Sometimes this is already the case, as when the core is about to serve
> a request and already called mmc_claim_host(). In the other cases you
> would have to claim the host from here, but that will not work as you
> will hang in the runtime PM core layer doing that.
>
> Doesn't failing to restore the tuning values here cause an error when
> trying to serve the next request? Returning -EILSEQ for that request,
> tells the core to re-tune in the error path, would that be okay?
Yes, I expect so.
> I think the important part here, is to make sure your host driver
> remains in an operational state (perhaps you may need to track this
> error and/or do some internal reset) - so it can return -EILSEQ for
> the next request.
For example by setting a field in the private host structure such
that tmio_mmc_finish_request can set cmd->error = -EILSEQ ?
> > + }
> > +
> > return 0;
> > }
> > EXPORT_SYMBOL(tmio_mmc_host_runtime_resume);
> > --
> > 2.7.0.rc3.207.g0ac5344
> >
> > --
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>
> Kind regards
> Uffe
>
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