CONFIG_MTD_ROM and suspend-to-RAM

CONFIG_MTD_ROM and suspend-to-RAM

[Uwe Kleine-König]

Hello,

I have a machine with a CFI flash using the physmap-flash mapping
driver.

The problem after the failed detection (as reported earlier on the
list[1]) is that if my kernel has CONFIG_MTD_ROM map_rom_probe() is
called, which doesn't assign mtd->suspend and returns success.

Then when I do

	echo mem > /sys/power/state

physmap_flash_suspend is called which does:

	for (i = 0; i < MAX_RESOURCES && info->mtd[i]; i++)
		ret |= info->mtd[i]->suspend(info->mtd[i]);

	return ret;

Unsurprisingly this results in an Oops.

IMHO both functions should behave better.  map_rom_probe should do some
probing (not sure this is possible though) and physmap_flash_suspend
should only call suspend if it's non-NULL.  Moreover
physmap_flash_suspend mangles the return value.  I would prefer to break
the loop after the first failure (and probably resume the already
suspended parts).  Moreover IIRC resume isn't called if suspend failed,
so there might be some chips that stay suspended after a failing
suspend.

I will come up with a patch addressing the physmap problems, but I don't
know map_rom and don't have a chip for that, so I will leave that to
someone else.

Best regards
Uwe

[1] http://thread.gmane.org/gmane.linux.drivers.mtd/22209

-- 
Uwe Kleine-König, Software Engineer
Digi International GmbH Branch Breisach, Küferstrasse 8, 79206 Breisach, Germany
Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962

[PATCH] [MTD] physmap: only call suspend and resume callbacks if non-NULL

[Uwe Kleine-König]

Signed-off-by: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
---
 drivers/mtd/maps/physmap.c |   12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/maps/physmap.c b/drivers/mtd/maps/physmap.c
index 183255f..f04061f 100644
--- a/drivers/mtd/maps/physmap.c
+++ b/drivers/mtd/maps/physmap.c
@@ -202,8 +202,10 @@ static int physmap_flash_suspend(struct platform_device *dev, pm_message_t state
 	int ret = 0;
 	int i;
 
-	for (i = 0; i < MAX_RESOURCES && info->mtd[i]; i++)
-		ret |= info->mtd[i]->suspend(info->mtd[i]);
+	for (i = 0; i < MAX_RESOURCES && info->mtd[i]; i++) {
+		if (info->mtd[i]->suspend)
+			ret |= info->mtd[i]->suspend(info->mtd[i]);
+	}
 
 	return ret;
 }
@@ -213,8 +215,10 @@ static int physmap_flash_resume(struct platform_device *dev)
 	struct physmap_flash_info *info = platform_get_drvdata(dev);
 	int i;
 
-	for (i = 0; i < MAX_RESOURCES && info->mtd[i]; i++)
-		info->mtd[i]->resume(info->mtd[i]);
+	for (i = 0; i < MAX_RESOURCES && info->mtd[i]; i++) {
+		if (info->mtd[i]->resume)
+			info->mtd[i]->resume(info->mtd[i]);
+	}
 
 	return 0;
 }
-- 
1.5.6.2

Re: [PATCH] [MTD] physmap: only call suspend and resume callbacks if non-NULL

[Robert Jarzmik]

Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com> writes:

> Signed-off-by: Uwe Kleine-König <Uwe.Kleine-Koenig@digi.com>
> ---
>  drivers/mtd/maps/physmap.c |   12 ++++++++----
>  1 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/maps/physmap.c b/drivers/mtd/maps/physmap.c
> index 183255f..f04061f 100644
> --- a/drivers/mtd/maps/physmap.c
> +++ b/drivers/mtd/maps/physmap.c
> @@ -202,8 +202,10 @@ static int physmap_flash_suspend(struct platform_device *dev, pm_message_t state
The same patch was submitted to this ML a while ago,
http://lists.infradead.org/pipermail/linux-mtd/2008-June/022023.html

It has not made it's way upstream, though ...

--
Robert

Re: [PATCH] [MTD] physmap: only call suspend and resume callbacks if non-NULL

[Uwe Kleine-König]

Hello Robert,

Robert Jarzmik wrote:
> The same patch was submitted to this ML a while ago,
> http://lists.infradead.org/pipermail/linux-mtd/2008-June/022023.html
> 
> It has not made it's way upstream, though ...
Ah, OK.  So please consider my mail as an additional Acked-by:

Thanks,
Uwe

-- 
Uwe Kleine-König, Software Engineer
Digi International GmbH Branch Breisach, Küferstrasse 8, 79206 Breisach, Germany
Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962