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>
This commit is contained in:
parent
703aae3d09
commit
19d614a45a
1 changed files with 12 additions and 7 deletions
|
@ -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),
|
||||
|
|
Reference in a new issue