diff options
| author | Sujit Reddy Thumma <sthumma@codeaurora.org> | 2014-01-10 10:58:54 +0530 |
|---|---|---|
| committer | Subhash Jadavani <subhashj@codeaurora.org> | 2016-05-27 10:29:00 -0700 |
| commit | d90d5901faba22e9bc67ade166de12b63412c44c (patch) | |
| tree | 817cb69fbf8728a2a55be2afa480796fb5b59773 /drivers | |
| parent | e8279c90212b2dc999e84e23696818e2d249dbad (diff) | |
mmc: sdhci-msm: Fix clock gating while voltage switch is in progress
CLK_PWRSAVE bit in vendor specific register gates the output clock to
card automatically if there are no data/cmd operations.
According the SD3.0 voltage switch sequence the host should provide
clock to the card for atleast one millisecond before DAT[3:0] lines
are pulled high by the card. In this case if power save bit is enabled
it might auto-gate clocks even before the card completes voltage
switch sequence.
Fix this by disabling power save operation when the clocks are turned
off and enable only when clock rate is >400KHz i.e., end of initialization.
CRs-Fixed: 589992
Change-Id: If82d6d2e303b8d1189b76712e514f41fe6e2cf8b
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/mmc/host/sdhci-msm.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c index d29ed9f3baec..4ebbcfaa2fab 100644 --- a/drivers/mmc/host/sdhci-msm.c +++ b/drivers/mmc/host/sdhci-msm.c @@ -2,7 +2,7 @@ * drivers/mmc/host/sdhci-msm.c - Qualcomm Technologies, Inc. MSM SDHCI Platform * driver source file * - * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved. + * Copyright (c) 2012-2014, The Linux Foundation. All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 and @@ -2453,6 +2453,12 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock) bool curr_pwrsave; if (!clock) { + /* + * disable pwrsave to ensure clock is not auto-gated until + * the rate is >400KHz (initialization complete). + */ + writel_relaxed(readl_relaxed(host->ioaddr + CORE_VENDOR_SPEC) & + ~CORE_CLK_PWRSAVE, host->ioaddr + CORE_VENDOR_SPEC); sdhci_msm_prepare_clocks(host, false); host->clock = clock; goto out; |