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!?
> + }
> +
> 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.
> + } 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().
> + }
> +
> + 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?
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.
> + }
> +
> 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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