On Fri, Aug 26, 2016 at 10:01:35AM +0200, Ulf Hansson wrote:
> On 25 August 2016 at 14:04, Simon Horman <horms@xxxxxxxxxxxx> wrote:
> > On Tue, Aug 23, 2016 at 05:02:56PM +0200, Ulf Hansson wrote:
...
> >> >> I am wondering whether it would it be possible to keep a cache of the
> >> >> currently used tuning values and then restore these values at
> >> >> runtime_resume?
> >> >>
> >> >> In that way you wouldn't need to force new re-tuning cycle here.
> >> >
> >> > I will check with the hardware people to see if it is practical from
> >> > that POV.
> >>
> >> Okay!
> >
> > The feedback I received is something like this:
> >
> > * The tap values calculated during retuning depend on the temperature of
> > the SoC and card.
> > * So after resume the values may be invalid.
>
> They values may also become invalid during long continues transfers,
> which prevents the ->runtime_suspend() callback to be invoked -
> because the temperature may increase.
>
> > * It may be possible to re-use the TAP values and re-tune if a transfer
> > fails but the people I spoke with were unsure of the merit of that
> > approach
>
> There's is a huge benefit!
>
> You will get a significant decreased latency at ->runtime_resume() as
> you don't need to run a complete re-tuning cycle.
>
> I can't really give you fresh numbers as it's a long time I tried this
> myself, although if you did some measurements on this it would be
> nice! :-)
>
> >
> > Personally my feeling is that we should initiate a retune on resume for
> > now as that seems to be the safest option.
>
> I don't agree. :-) I think it's better to postpone re-tune until it's
> actually needed.
>
> Re-tune happens in the request error handling path, but also if you
> configure a re-tuning period. That ought to be sufficient, don't you
> think?
Hi Ulf,
Is something like this close to what you have in mind?
diff --git a/drivers/mmc/host/sh_mobile_sdhi.c b/drivers/mmc/host/sh_mobile_sdhi.c
index 94e79449c533..fc43cf5ce958 100644
--- a/drivers/mmc/host/sh_mobile_sdhi.c
+++ b/drivers/mmc/host/sh_mobile_sdhi.c
@@ -357,11 +357,9 @@ static void sh_mobile_sdhi_prepare_tuning(struct tmio_mmc_host *host,
#define SH_MOBILE_SDHI_MAX_TAP 3
-static int sh_mobile_sdhi_select_tuning(struct tmio_mmc_host *host,
- bool *tap, int tap_size)
+static int sh_mobile_sdhi_select_tuning(struct tmio_mmc_host *host)
{
struct sh_mobile_sdhi *priv = host_to_priv(host);
- unsigned long tap_num; /* total number of taps */
unsigned long tap_cnt; /* counter of tuning success */
unsigned long tap_set; /* tap position */
unsigned long tap_start;/* start position of tuning success */
@@ -372,14 +370,6 @@ static int sh_mobile_sdhi_select_tuning(struct tmio_mmc_host *host,
/* Clear SCC_RVSREQ */
sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_RVSREQ, 0);
- /* Select SCC */
- tap_num = (sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_DTCNTL) >>
- SH_MOBILE_SDHI_SCC_DTCNTL_TAPNUM_SHIFT) &
- SH_MOBILE_SDHI_SCC_DTCNTL_TAPNUM_MASK;
-
- if (tap_num * 2 != tap_size)
- return -EINVAL;
-
/*
* Find the longest consecutive run of successful probes. If that
* is more than SH_MOBILE_SDHI_MAX_TAP probes long then use the
@@ -389,8 +379,8 @@ static int sh_mobile_sdhi_select_tuning(struct tmio_mmc_host *host,
ntap = 0;
tap_start = 0;
tap_end = 0;
- for (i = 0; i < tap_num * 2; i++) {
- if (tap[i] == 0)
+ for (i = 0; i < host->tap_num * 2; i++) {
+ if (test_bit(i, host->taps))
ntap++;
else {
if (ntap > tap_cnt) {
@@ -409,7 +399,7 @@ static int sh_mobile_sdhi_select_tuning(struct tmio_mmc_host *host,
}
if (tap_cnt >= SH_MOBILE_SDHI_MAX_TAP)
- tap_set = (tap_start + tap_end) / 2 % tap_num;
+ tap_set = (tap_start + tap_end) / 2 % host->tap_num;
else
return -EIO;
diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
index c932fe876690..4186045cce0d 100644
--- a/drivers/mmc/host/tmio_mmc.h
+++ b/drivers/mmc/host/tmio_mmc.h
@@ -171,8 +171,12 @@ struct tmio_mmc_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, bool *tap,
- int tap_size);
+ 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;
+ bool use_saved_taps;
};
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 ded8fa53e0a0..2b5c8b090ed3 100644
--- a/drivers/mmc/host/tmio_mmc_pio.c
+++ b/drivers/mmc/host/tmio_mmc_pio.c
@@ -773,43 +773,50 @@ static void tmio_mmc_hw_reset(struct mmc_host *mmc)
static int tmio_mmc_execute_tuning(struct mmc_host *mmc, u32 opcode)
{
struct tmio_mmc_host *host = mmc_priv(mmc);
- unsigned int num;
- int i, ret = 0;
- bool *tap;
+ int ret = 0;
- if (!host->init_tuning || !host->select_tuning)
- /* Tuning is not supported */
- goto out;
+ if (!host->tap_num) {
+ if (!host->init_tuning || !host->select_tuning)
+ /* Tuning is not supported */
+ goto out;
- num = host->init_tuning(host);
- if (!num)
- /* Tuning is not supported */
- goto out;
+ host->tap_num = host->init_tuning(host);
+ if (!host->tap_num)
+ /* Tuning is not supported */
+ goto out;
- tap = kmalloc(num * 2 * sizeof(*tap), GFP_KERNEL);
- if (!tap) {
- ret = -ENOMEM;
- 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");
+
+ host->use_saved_taps = false;
}
- /* Issue CMD19 twice for each tap */
- for (i = 0; i < 2 * num; i++) {
- if (host->prepare_tuning)
- host->prepare_tuning(host, i % num);
+ if (!host->use_saved_taps) {
+ int i;
+
+ bitmap_zero(host->taps, host->tap_num * 2);
- ret = mmc_send_tuning(mmc, opcode, NULL);
- if (ret && ret != -EILSEQ)
- goto err_free;
- tap[i] = (ret != 0);
+ /* 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);
- mdelay(1);
+ 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, tap, num * 2);
+ ret = host->select_tuning(host);
-err_free:
- kfree(tap);
out:
+ host->use_saved_taps = false;
if (ret < 0) {
dev_warn(&host->pdev->dev, "Tuning procedure failed\n");
mmc_hw_reset(mmc);
@@ -1271,6 +1278,7 @@ int tmio_mmc_host_runtime_suspend(struct device *dev)
mmc_retune_timer_stop(host->mmc);
mmc_retune_needed(host->mmc);
+ host->use_saved_taps = true;
tmio_mmc_disable_mmc_irqs(host, TMIO_MASK_ALL);
--
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