diff options
| author | Michael Walle <michael@walle.cc> | 2021-09-10 11:20:52 +0200 |
|---|---|---|
| committer | Peng Fan <peng.fan@nxp.com> | 2021-09-13 11:46:50 +0800 |
| commit | 285edfd7821e79de579b0bf1a7328dead2304a0b (patch) | |
| tree | 8065f834531b36c340486cd1d5244834db977e84 | |
| parent | fb8c2e8fa936f8ebe4b7cc822abe33ff620585cd (diff) | |
| download | u-boot-285edfd7821e79de579b0bf1a7328dead2304a0b.tar.gz | |
mmc: fsl_esdhc: remove 1ms sleep in esdhc_send_cmd_common()
Since the beginning of this driver which was initially for the MPC8379
and MPC8536 SoCs, there is this spurious 1ms delay. According to the
comment it should actually be only 8 clock cycles. Esp. during EFI block
transfers, this 1ms add up to a significant delay and slows down EFI
boot.
I couldn't find any mention in the MPC8536 that there should be a delay
of 8 clock cycles between commands. The SD card specification mentions that
the clock has to be left enabled for 8 cycles after a command or
response. But I don't see how this delay will help with this.
Go ahead and just remove it. If there will ever be any regression we can
introduce a compile time flag, but for now I'd like to keep it simple.
In the split off imx driver this delay was also removed in commit
9098682200e6 ("mmc: fsl_esdhc_imx: remove the 1ms delay before sending
command").
Signed-off-by: Michael Walle <michael@walle.cc>
| -rw-r--r-- | drivers/mmc/fsl_esdhc.c | 7 |
1 files changed, 0 insertions, 7 deletions
diff --git a/drivers/mmc/fsl_esdhc.c b/drivers/mmc/fsl_esdhc.c index 1d98fa65c4..ebb307e950 100644 --- a/drivers/mmc/fsl_esdhc.c +++ b/drivers/mmc/fsl_esdhc.c @@ -361,13 +361,6 @@ static int esdhc_send_cmd_common(struct fsl_esdhc_priv *priv, struct mmc *mmc, while (esdhc_read32(®s->prsstat) & PRSSTAT_DLA) ; - /* Wait at least 8 SD clock cycles before the next command */ - /* - * Note: This is way more than 8 cycles, but 1ms seems to - * resolve timing issues with some cards - */ - udelay(1000); - /* Set up for a data transfer if we have one */ if (data) { err = esdhc_setup_data(priv, mmc, data); |