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mmc: mediatek: perfer to use rise edge latching

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in our host design, rise edge latching is more stable than fall edge
latching. so that if rise edge has enough margin, no need scan fall edge.

Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Chaotian Jing 2016-06-30 10:01:01 +08:00 committed by Ulf Hansson
parent ddc713878f
commit ae9c657e62
1 changed files with 14 additions and 9 deletions
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23
drivers/mmc/host/mtk-sd.c
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@ -1328,7 +1328,7 @@ static int msdc_tune_response(struct mmc_host *mmc, u32 opcode)
{
struct msdc_host *host = mmc_priv(mmc);
u32 rise_delay = 0, fall_delay = 0;
struct msdc_delay_phase final_rise_delay, final_fall_delay;
struct msdc_delay_phase final_rise_delay, final_fall_delay = { 0,};
u8 final_delay, final_maxlen;
int cmd_err;
int i;
@ -1341,6 +1341,11 @@ static int msdc_tune_response(struct mmc_host *mmc, u32 opcode)
if (!cmd_err)
rise_delay |= (1 << i);
}
final_rise_delay = get_best_delay(host, rise_delay);
/* if rising edge has enough margin, then do not scan falling edge */
if (final_rise_delay.maxlen >= 10 ||
(final_rise_delay.start == 0 && final_rise_delay.maxlen >= 4))
goto skip_fall;
sdr_set_bits(host->base + MSDC_IOCON, MSDC_IOCON_RSPL);
for (i = 0; i < PAD_DELAY_MAX; i++) {
@ -1350,10 +1355,9 @@ static int msdc_tune_response(struct mmc_host *mmc, u32 opcode)
if (!cmd_err)
fall_delay |= (1 << i);
}
final_rise_delay = get_best_delay(host, rise_delay);
final_fall_delay = get_best_delay(host, fall_delay);
skip_fall:
final_maxlen = max(final_rise_delay.maxlen, final_fall_delay.maxlen);
if (final_maxlen == final_rise_delay.maxlen) {
sdr_clr_bits(host->base + MSDC_IOCON, MSDC_IOCON_RSPL);
@ -1374,7 +1378,7 @@ static int msdc_tune_data(struct mmc_host *mmc, u32 opcode)
{
struct msdc_host *host = mmc_priv(mmc);
u32 rise_delay = 0, fall_delay = 0;
struct msdc_delay_phase final_rise_delay, final_fall_delay;
struct msdc_delay_phase final_rise_delay, final_fall_delay = { 0,};
u8 final_delay, final_maxlen;
int i, ret;
@ -1387,6 +1391,11 @@ static int msdc_tune_data(struct mmc_host *mmc, u32 opcode)
if (!ret)
rise_delay |= (1 << i);
}
final_rise_delay = get_best_delay(host, rise_delay);
/* if rising edge has enough margin, then do not scan falling edge */
if (final_rise_delay.maxlen >= 10 ||
(final_rise_delay.start == 0 && final_rise_delay.maxlen >= 4))
goto skip_fall;
sdr_set_bits(host->base + MSDC_IOCON, MSDC_IOCON_DSPL);
sdr_set_bits(host->base + MSDC_IOCON, MSDC_IOCON_W_DSPL);
@ -1397,14 +1406,10 @@ static int msdc_tune_data(struct mmc_host *mmc, u32 opcode)
if (!ret)
fall_delay |= (1 << i);
}
final_rise_delay = get_best_delay(host, rise_delay);
final_fall_delay = get_best_delay(host, fall_delay);
skip_fall:
final_maxlen = max(final_rise_delay.maxlen, final_fall_delay.maxlen);
/* Rising edge is more stable, prefer to use it */
if (final_rise_delay.maxlen >= 10)
final_maxlen = final_rise_delay.maxlen;
if (final_maxlen == final_rise_delay.maxlen) {
sdr_clr_bits(host->base + MSDC_IOCON, MSDC_IOCON_DSPL);
sdr_clr_bits(host->base + MSDC_IOCON, MSDC_IOCON_W_DSPL);