for (clk = 0x80000080; new_clock >= (clock << 1); clk >>= 1)
clock <<= 1;
... is too tricky, hence I replaced with
roundup_pow_of_two(divisor) >> 2
'(clk >> 22) & 0x1' is the bit test for the 1/1 divisor, but
it is not clear. 'divisor <= 1' is easier to understand.
Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
---
drivers/mmc/host/renesas_sdhi_core.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
index a15fb2e..98391e9 100644
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -158,7 +158,8 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
static void renesas_sdhi_set_clock(struct tmio_mmc_host *host,
unsigned int new_clock)
{
- u32 clk = 0, clock;
+ unsigned int clock, divisor;
+ u32 clk = 0;
sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, ~CLK_CTL_SCLKEN &
sd_ctrl_read16(host, CTL_SD_CARD_CLK_CTL));
@@ -166,14 +167,18 @@ static void renesas_sdhi_set_clock(struct tmio_mmc_host *host,
if (new_clock == 0)
goto out;
- clock = renesas_sdhi_clk_update(host, new_clock) / 512;
+ clock = renesas_sdhi_clk_update(host, new_clock);
- for (clk = 0x80000080; new_clock >= (clock << 1); clk >>= 1)
- clock <<= 1;
+ divisor = clock / new_clock;
- /* 1/1 clock is option */
- if ((host->pdata->flags & TMIO_MMC_CLK_ACTUAL) && ((clk >> 22) & 0x1))
- clk |= 0xff;
+ /*
+ * bit7 set: 1/512, ... bit0 set:1/4, all bits clear: 1/2
+ * all bits set: 1/1 (Renesas-specific extension?)
+ */
+ if ((host->pdata->flags & TMIO_MMC_CLK_ACTUAL) && divisor <= 1)
+ clk = 0xff;
+ else
+ clk = roundup_pow_of_two(divisor) >> 2;
sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, clk & CLK_CTL_DIV_MASK);
if (!(host->pdata->flags & TMIO_MMC_MIN_RCAR2))
--
2.7.4
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