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mmc: renesas_sdhi: improve TAP selection if all TAPs are good

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When tuning HS400, if all TAPS are good, we can utilize the SMPCMP
register to select the optimal TAP. For that, we populate a second
bitmap with SMPCMP results and query it in case the regular bitmap is
full (= all good).

Signed-off-by: Masaharu Hayakawa <masaharu.hayakawa.ry@renesas.com>
Signed-off-by: Takeshi Saito <takeshi.saito.xv@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20200408094638.10375-4-wsa+renesas@sang-engineering.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Wolfram Sang 2020-04-08 11:46:38 +02:00 committed by Ulf Hansson
parent ec4fc1acf3
commit 5fb6bf51f6
2 changed files with 25 additions and 3 deletions
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2
drivers/mmc/host/renesas_sdhi.h
View File

@ -61,6 +61,8 @@ struct renesas_sdhi {
/* Tuning values: 1 for success, 0 for failure */
DECLARE_BITMAP(taps, BITS_PER_LONG);
/* Sampling data comparison: 1 for match, 0 for mismatch */
DECLARE_BITMAP(smpcmp, BITS_PER_LONG);
unsigned int tap_num;
unsigned long tap_set;
};

26
drivers/mmc/host/renesas_sdhi_core.c
View File

@ -428,7 +428,8 @@ static int renesas_sdhi_select_tuning(struct tmio_mmc_host *host)
{
struct renesas_sdhi *priv = host_to_priv(host);
unsigned int tap_start = 0, tap_end = 0, tap_cnt = 0, rs, re, i;
unsigned int taps_size = priv->tap_num * 2;
unsigned int taps_size = priv->tap_num * 2, min_tap_row;
unsigned long *bitmap;
priv->doing_tune = false;
sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_RVSREQ, 0);
@ -443,6 +444,21 @@ static int renesas_sdhi_select_tuning(struct tmio_mmc_host *host)
if (!test_bit(i, priv->taps))
clear_bit(i + offset, priv->taps);
if (!test_bit(i, priv->smpcmp))
clear_bit(i + offset, priv->smpcmp);
}
/*
* If all TAP are OK, the sampling clock position is selected by
* identifying the change point of data.
*/
if (bitmap_full(priv->taps, taps_size)) {
bitmap = priv->smpcmp;
min_tap_row = 1;
} else {
bitmap = priv->taps;
min_tap_row = SH_MOBILE_SDHI_MIN_TAP_ROW;
}
/*
@ -450,7 +466,7 @@ static int renesas_sdhi_select_tuning(struct tmio_mmc_host *host)
* is at least SH_MOBILE_SDHI_MIN_TAP_ROW probes long then use the
* center index as the tap, otherwise bail out.
*/
bitmap_for_each_set_region(priv->taps, rs, re, 0, taps_size) {
bitmap_for_each_set_region(bitmap, rs, re, 0, taps_size) {
if (re - rs > tap_cnt) {
tap_end = re;
tap_start = rs;
@ -458,7 +474,7 @@ static int renesas_sdhi_select_tuning(struct tmio_mmc_host *host)
}
}
if (tap_cnt >= SH_MOBILE_SDHI_MIN_TAP_ROW)
if (tap_cnt >= min_tap_row)
priv->tap_set = (tap_start + tap_end) / 2 % priv->tap_num;
else
return -EIO;
@ -491,6 +507,7 @@ static int renesas_sdhi_execute_tuning(struct tmio_mmc_host *host, u32 opcode)
priv->doing_tune = true;
bitmap_zero(priv->taps, priv->tap_num * 2);
bitmap_zero(priv->smpcmp, priv->tap_num * 2);
/* Issue CMD19 twice for each tap */
for (i = 0; i < 2 * priv->tap_num; i++) {
@ -499,6 +516,9 @@ static int renesas_sdhi_execute_tuning(struct tmio_mmc_host *host, u32 opcode)
if (mmc_send_tuning(host->mmc, opcode, NULL) == 0)
set_bit(i, priv->taps);
if (sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_SMPCMP) == 0)
set_bit(i, priv->smpcmp);
}
return renesas_sdhi_select_tuning(host);