[U-Boot] [PATCH] mmc: omap: follow TRM procedure to power on cards

[U-Boot] [PATCH] mmc: omap: follow TRM procedure to power on cards

[Grazvydas Ignotas]

According to OMAP3 TRM, PBIASLITEPWRDNZ bits must be cleared while MMC
power supply is being enabled and is ramping up (those bits might be
left set by the previous bootloader). It doesn't say what happens if
this procedure is violated, but better not to risk here and do things
as required.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
---
 drivers/mmc/omap_hsmmc.c |   16 +++++++++++-----
 1 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/omap_hsmmc.c b/drivers/mmc/omap_hsmmc.c
index 12ff0a2..e9e1d2a 100644
--- a/drivers/mmc/omap_hsmmc.c
+++ b/drivers/mmc/omap_hsmmc.c
@@ -62,15 +62,21 @@ static void omap4_vmmc_pbias_config(struct mmc *mmc)
 
 unsigned char mmc_board_init(struct mmc *mmc)
 {
-#if defined(CONFIG_TWL4030_POWER)
-	twl4030_power_mmc_init();
-#endif
-
 #if defined(CONFIG_OMAP34XX)
 	t2_t *t2_base = (t2_t *)T2_BASE;
 	struct prcm *prcm_base = (struct prcm *)PRCM_BASE;
+	u32 pbias_lite;
 
-	writel(readl(&t2_base->pbias_lite) | PBIASLITEPWRDNZ1 |
+	pbias_lite = readl(&t2_base->pbias_lite);
+	pbias_lite &= ~(PBIASLITEPWRDNZ1 | PBIASLITEPWRDNZ0);
+	writel(pbias_lite, &t2_base->pbias_lite);
+#endif
+#if defined(CONFIG_TWL4030_POWER)
+	twl4030_power_mmc_init();
+	mdelay(100);	/* ramp-up delay from Linux code */
+#endif
+#if defined(CONFIG_OMAP34XX)
+	writel(pbias_lite | PBIASLITEPWRDNZ1 |
 		PBIASSPEEDCTRL0 | PBIASLITEPWRDNZ0,
 		&t2_base->pbias_lite);
 
-- 
1.7.0.4

[U-Boot] [PATCH] mmc: omap: follow TRM procedure to power on cards

[Tom Rini]

On 03/19/2012 06:50 AM, Grazvydas Ignotas wrote:
> According to OMAP3 TRM, PBIASLITEPWRDNZ bits must be cleared while MMC
> power supply is being enabled and is ramping up (those bits might be
> left set by the previous bootloader). It doesn't say what happens if
> this procedure is violated, but better not to risk here and do things
> as required.

While in favor of correctness (and putting / moving up reconciling Linux 
and U-Boot omap MMC drivers on my TODO list), does this help with the 
problem you had reported before?  Thanks!

-- 
Tom

[U-Boot] [PATCH] mmc: omap: follow TRM procedure to power on cards

[Grazvydas Ignotas]

On Mon, Mar 19, 2012 at 6:44 PM, Tom Rini <trini@ti.com> wrote:
> On 03/19/2012 06:50 AM, Grazvydas Ignotas wrote:
>>
>> According to OMAP3 TRM, PBIASLITEPWRDNZ bits must be cleared while MMC
>> power supply is being enabled and is ramping up (those bits might be
>> left set by the previous bootloader). It doesn't say what happens if
>> this procedure is violated, but better not to risk here and do things
>> as required.
>
>
> While in favor of correctness (and putting / moving up reconciling Linux and
> U-Boot omap MMC drivers on my TODO list), does this help with the problem
> you had reported before? ?Thanks!

Unfortunately not, but I'm still looking for a cause and might have
some more similar patches.


-- 
Gra?vydas

[U-Boot] [PATCH] mmc: omap: follow TRM procedure to power on cards

[Tom Rini]

On Mon, Mar 19, 2012 at 03:50:53PM +0200, Grazvydas Ignotas wrote:
> According to OMAP3 TRM, PBIASLITEPWRDNZ bits must be cleared while MMC
> power supply is being enabled and is ramping up (those bits might be
> left set by the previous bootloader). It doesn't say what happens if
> this procedure is violated, but better not to risk here and do things
> as required.
> 
> Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>

Acked-by: Tom Rini <trini@ti.com>

Andy, please take this via your tree, thanks!

-- 
Tom
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