| Message ID | 1314856275-12131-1-git-send-email-tony.lin@freescale.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Sep 01, 2011 at 01:51:15PM +0800, Tony Lin wrote: > 1ms is enough for hardware to change the clock to stable. > 100ms is too long. How do you know that? Can you be sure for PowerPC as well? Have you researched why the original author of the code has chosen that value? If so, please update your commit message with such infos.
> -----Original Message----- > From: Wolfram Sang [mailto:w.sang@pengutronix.de] > Sent: Thursday, September 01, 2011 1:55 PM > To: Lin Tony-B19295 > Cc: linux-mmc@vger.kernel.org; linux-arm-kernel@lists.infradead.org; > cjb@laptop.org > Subject: Re: [PATCH 1/1] mmc: sdhci-esdhc: Change delay after setting > clock from 100ms to 1ms > > On Thu, Sep 01, 2011 at 01:51:15PM +0800, Tony Lin wrote: > > 1ms is enough for hardware to change the clock to stable. > > 100ms is too long. > > How do you know that? Can you be sure for PowerPC as well? Have you > researched why the original author of the code has chosen that value? If > so, please update your commit message with such infos. > I got this confirmation by IC simulation, but sorry I just noticed that's also used for PPC. I can update the information after got confirmation from author. > -- > Pengutronix e.K. | Wolfram Sang > | > Industrial Linux Solutions | http://www.pengutronix.de/ > | -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/mmc/host/sdhci-esdhc.h b/drivers/mmc/host/sdhci-esdhc.h index c3b08f1..b97b2f5 100644 --- a/drivers/mmc/host/sdhci-esdhc.h +++ b/drivers/mmc/host/sdhci-esdhc.h @@ -73,7 +73,7 @@ static inline void esdhc_set_clock(struct sdhci_host *host, unsigned int clock) | (div << ESDHC_DIVIDER_SHIFT) | (pre_div << ESDHC_PREDIV_SHIFT)); sdhci_writel(host, temp, ESDHC_SYSTEM_CONTROL); - mdelay(100); + mdelay(1); out: host->clock = clock; }
1ms is enough for hardware to change the clock to stable. 100ms is too long. Signed-off-by: Tony Lin <tony.lin@freescale.com> --- drivers/mmc/host/sdhci-esdhc.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)