Paul Walmsley <paul@xxxxxxxxx> writes:
> On Mon, 4 Feb 2013, Rajendra Nayak wrote:
>
>> OMAP4 CHIP level PM works only with newer bootloaders. The
>> dependency on the bootloader comes from the fact that the
>> kernel is missing reset and initialization code for some
>> devices.
>>
>> While the right thing to do is to add reset and init code in
>> the kernel, for some co-processor IP blocks like DSP and IVA
>> it means downloading firmware into each one of them to execute
>> idle instructions.
>>
>> While a feasible solution is worked upon on how such IP blocks
>> can be better handled in the kernel, in the interim, to avoid
>> any further frustration to users testing PM on OMAP4 and finding
>> it broken, warn them about the bootloader being a possible
>> cause.
>>
>> Signed-off-by: Rajendra Nayak <rnayak@xxxxxx>
>> Cc: Tero Kristo <t-kristo@xxxxxx>
>> Cc: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
>> Cc: R Sricharan <r.sricharan@xxxxxx>
>
> Thanks Rajendra, I appreciate the patch. I've tweaked it slightly and the
> following is what's queued here; hopefully it can go in for v3.9.
>
>
> - Paul
>
> From: Rajendra Nayak <rnayak@xxxxxx>
> Date: Mon, 4 Feb 2013 17:54:43 +0530
> Subject: [PATCH] ARM: OMAP4: PM: Warn users about usage of older bootloaders
>
> OMAP4 CHIP level PM works only with newer bootloaders. The
> dependency on the bootloader comes from the fact that the
> kernel is missing reset and initialization code for some
> devices.
>
> While the right thing to do is to add reset and init code in
> the kernel, for some co-processor IP blocks like DSP and IVA
> it means downloading firmware into each one of them to execute
> idle instructions.
>
> While a feasible solution is worked upon on how such IP blocks
> can be better handled in the kernel, in the interim, to avoid
> any further frustration to users testing PM on OMAP4 and finding
> it broken, warn them about the bootloader being a possible
> cause.
>
> Signed-off-by: Rajendra Nayak <rnayak@xxxxxx>
> Cc: Tero Kristo <t-kristo@xxxxxx>
> Cc: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
> Cc: R Sricharan <r.sricharan@xxxxxx>
> [paul@xxxxxxxxx: tweaked warning messages and comments slightly]
> Signed-off-by: Paul Walmsley <paul@xxxxxxxxx>
FWIW
Acked-by: Kevin Hilman <khilman@xxxxxxxxxx>
> ---
> arch/arm/mach-omap2/pm44xx.c | 19 ++++++++++++++++++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mach-omap2/pm44xx.c b/arch/arm/mach-omap2/pm44xx.c
> index aa6fd98..502ed9b 100644
> --- a/arch/arm/mach-omap2/pm44xx.c
> +++ b/arch/arm/mach-omap2/pm44xx.c
> @@ -77,8 +77,18 @@ static int omap4_pm_suspend(void)
> omap_set_pwrdm_state(pwrst->pwrdm, pwrst->saved_state);
> pwrdm_set_logic_retst(pwrst->pwrdm, pwrst->saved_logic_state);
> }
> - if (ret)
> + if (ret) {
> pr_crit("Could not enter target state in pm_suspend\n");
> + /*
> + * OMAP4 chip PM currently works only with certain (newer)
> + * versions of bootloaders. This is due to missing code in the
> + * kernel to properly reset and initialize some devices.
> + * Warn the user about the bootloader version being one of the
> + * possible causes.
> + * http://www.spinics.net/lists/arm-kernel/msg218641.html
> + */
> + pr_warn("A possible cause could be an old bootloader - try u-boot >= v2012.07\n");
> + }
> else
> pr_info("Successfully put all powerdomains to target state\n");
>
> @@ -146,6 +156,13 @@ int __init omap4_pm_init(void)
> }
>
> pr_err("Power Management for TI OMAP4.\n");
> + /*
> + * OMAP4 chip PM currently works only with certain (newer)
> + * versions of bootloaders. This is due to missing code in the
> + * kernel to properly reset and initialize some devices.
> + * http://www.spinics.net/lists/arm-kernel/msg218641.html
> + */
> + pr_warn("u-boot >= v2012.07 is required for full PM support\n");
>
> ret = pwrdm_for_each(pwrdms_setup, NULL);
> if (ret) {
--
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