diff options
| author | Ulf Hansson <ulf.hansson@stericsson.com> | 2011-11-01 12:03:59 +0100 |
|---|---|---|
| committer | Philippe Langlais <philippe.langlais@stericsson.com> | 2012-05-22 11:03:02 +0200 |
| commit | 5137c4ea06a48c3a9e47c8fbbb81701db9e816f9 (patch) | |
| tree | 09c3458ab2baadb1ba04dd48186f449c424331a8 | |
| parent | 4920bb837ad14634b8d8b257452442ac5d97a82f (diff) | |
mmc: mmci: Limit command frequency when using a levelshifter
Due to timing issues for command direction signaling when
using a levelshifter, we limit the frequency to 25 MHz while
sending commands. The frequency is just limited during the
command send/response, then it is restored to it's original
value.
ST-Ericsson ID: 355531
ST-Ericsson Linux next: -
ST-Ericsson FOSS-OUT ID: Trivial
Change-Id: I15d06e3c331a4db717a904937ce6ce60972d185e
Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/51785
| -rw-r--r-- | drivers/mmc/host/mmci.c | 15 | ||||
| -rw-r--r-- | drivers/mmc/host/mmci.h | 1 |
2 files changed, 16 insertions, 0 deletions
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c index e3d67089265..368f855ceac 100644 --- a/drivers/mmc/host/mmci.c +++ b/drivers/mmc/host/mmci.c @@ -789,6 +789,14 @@ mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c) if (/*interrupt*/0) c |= MCI_CPSM_INTERRUPT; + /* + * For levelshifters we must not use more than 25MHz when + * sending commands. + */ + host->cclk_desired = host->cclk; + if (host->plat->ios_handler && (host->cclk_desired > 25000000)) + mmci_set_clkreg(host, 25000000); + host->cmd = cmd; writel(cmd->arg, base + MMCIARGUMENT); @@ -881,6 +889,13 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd, cmd->resp[3] = readl(base + MMCIRESPONSE3); } + /* + * For levelshifters we might have decreased cclk to 25MHz when + * sending commands, then we restore the frequency here. + */ + if (host->plat->ios_handler && (host->cclk_desired > host->cclk)) + mmci_set_clkreg(host, host->cclk_desired); + if (!cmd->data || cmd->error) { /* Terminate the DMA transfer */ if (dma_inprogress(host)) { diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h index ba09a603787..5a17beafd05 100644 --- a/drivers/mmc/host/mmci.h +++ b/drivers/mmc/host/mmci.h @@ -186,6 +186,7 @@ struct mmci_host { unsigned int mclk; unsigned int cclk; + unsigned int cclk_desired; u32 pwr_reg; u32 clk_reg; u32 datactrl_reg; |