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| author | Michał Mirosław <mirq-linux@rere.qmqm.pl> | 2010-03-21 07:33:08 +0100 |
|---|---|---|
| committer | Chris Ball <cjb@laptop.org> | 2010-10-23 15:11:20 +0200 |
| commit | 19d614a45ae4beb4712bb50ba3d816ae3fe0f1f2 (patch) | |
| tree | f3f019eebd38d4fa73100593654d0d6dd4d75e6b /drivers/mmc/host/cb710-mmc.c | |
| parent | mmc: add a file to debugfs for changing host clock at runtime (diff) | |
| download | linux-19d614a45ae4beb4712bb50ba3d816ae3fe0f1f2.tar.xz linux-19d614a45ae4beb4712bb50ba3d816ae3fe0f1f2.zip | |
mmc: cb710: partially demystify clock selection
Clock divider selection in partially verified, so document known facts
in code.
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'drivers/mmc/host/cb710-mmc.c')
| -rw-r--r-- | drivers/mmc/host/cb710-mmc.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/drivers/mmc/host/cb710-mmc.c b/drivers/mmc/host/cb710-mmc.c index ca3bdc831900..ad61c4c11071 100644 --- a/drivers/mmc/host/cb710-mmc.c +++ b/drivers/mmc/host/cb710-mmc.c @@ -25,7 +25,7 @@ static const u8 cb710_src_freq_mhz[16] = { 50, 55, 60, 65, 70, 75, 80, 85 }; -static void cb710_mmc_set_clock(struct mmc_host *mmc, int hz) +static void cb710_mmc_select_clock_divider(struct mmc_host *mmc, int hz) { struct cb710_slot *slot = cb710_mmc_to_slot(mmc); struct pci_dev *pdev = cb710_slot_to_chip(slot)->pdev; @@ -33,8 +33,11 @@ static void cb710_mmc_set_clock(struct mmc_host *mmc, int hz) u32 divider_idx; int src_hz; - /* this is magic, unverifiable for me, unless I get - * MMC card with cables connected to bus signals */ + /* on CB710 in HP nx9500: + * src_freq_idx == 0 + * indexes 1-7 work as written in the table + * indexes 0,8-15 give no clock output + */ pci_read_config_dword(pdev, 0x48, &src_freq_idx); src_freq_idx = (src_freq_idx >> 16) & 0xF; src_hz = cb710_src_freq_mhz[src_freq_idx] * 1000000; @@ -46,13 +49,15 @@ static void cb710_mmc_set_clock(struct mmc_host *mmc, int hz) if (src_freq_idx) divider_idx |= 0x8; + else if (divider_idx == 0) + divider_idx = 1; cb710_pci_update_config_reg(pdev, 0x40, ~0xF0000000, divider_idx << 28); dev_dbg(cb710_slot_dev(slot), - "clock set to %d Hz, wanted %d Hz; flag = %d\n", + "clock set to %d Hz, wanted %d Hz; src_freq_idx = %d, divider_idx = %d|%d\n", src_hz >> cb710_clock_divider_log2[divider_idx & 7], - hz, (divider_idx & 8) != 0); + hz, src_freq_idx, divider_idx & 7, divider_idx & 8); } static void __cb710_mmc_enable_irq(struct cb710_slot *slot, @@ -512,7 +517,7 @@ static int cb710_mmc_powerup(struct cb710_slot *slot) #endif int err; - /* a lot of magic; see comment in cb710_mmc_set_clock() */ + /* a lot of magic for now */ dev_dbg(cb710_slot_dev(slot), "bus powerup\n"); cb710_dump_regs(chip, CB710_DUMP_REGS_MMC); err = cb710_wait_while_busy(slot, CB710_MMC_S2_BUSY_20); @@ -572,7 +577,7 @@ static void cb710_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) struct cb710_mmc_reader *reader = mmc_priv(mmc); int err; - cb710_mmc_set_clock(mmc, ios->clock); + cb710_mmc_select_clock_divider(mmc, ios->clock); if (!cb710_mmc_is_card_inserted(slot)) { dev_dbg(cb710_slot_dev(slot), |