Hi,
* Janusz Krzysztofik <[email protected]> [120430 11:15]:
> Dnia czwartek, 26 kwietnia 2012 08:20:59 Artem Bityutskiy pisze:
> > On Wed, 2012-04-25 at 19:01 +0200, Janusz Krzysztofik wrote:
> > > Both drivers use separate subsets of registers that belong to the
> OMAP1
> > > MPU I/O device, but are used for controlling different sets of I/O
> pins.
> > > The NAND driver reads/writes the folowing registers:
> > > - OMAP_MPUIO_INPUT_LATCH,
> > > - OMAP_MPUIO_OUTPUT,
> > > - OMAP_MPUIO_IO_CNTL,
> > > while the keypad driver - the following:
> > > - OMAP_MPUIO_KBR_LATCH,
> > > - OMAP_MPUIO_KBC,
> > > - OMAP_MPUIO_KBD_MASKIT
> > > - OMAP_MPUIO_GPIO_DEBOUNCING.
> > > Both subsets are non-overlapping, and we rely on the drivers being
> free
> > > of bugs and doing their job correctly, not stepping on each others'
> > > feet, I guess.
> >
> > First of all, I think this information should be in the commit
> message.
> > Also, some sort of comment in the driver code would be nice.
> >
> > If locking the memory region is too coarse approach, the should have a
> > small separate omap-specific MPUIO subsystem which will be used by
> > drivers to access MPUIO?
> >
> > Another question - should request_mem_region() be also removed from
> the
> > omap-gpio driver then? I think it is more sensible to put a comment
> > there that it is sharing MPIO with other drivers, instead of having
> an
> > illusion of exclusive memory region ownership.
> >
> > But this is up to the OMAP community - I can take this patch to my
> > l2-mtd tree if you get an ack from Tony or other OMAP guys.
>
> Tony,
> Would I get your Ack for this fix if I extend the commit message as Artem
> suggested? If not, what do you think should be a correct way to fix the
> regression?
Well how about adding some exported functions to drivers/gpio/gpio_omap.c
like omap_mpuio_latch?
For the regression fix, if you guys want to do what Janusz is suggesting,
then assuming the patch description also contains some decent long term
plan to properly fix it:
Acked-by: Tony Lindgren <[email protected]>
On Fri, 4 May 2012 10:11:25 Tony Lindgren wrote:
> Hi,
>
> * Janusz Krzysztofik <[email protected]> [120430 11:15]:
> > Dnia czwartek, 26 kwietnia 2012 08:20:59 Artem Bityutskiy pisze:
> > > On Wed, 2012-04-25 at 19:01 +0200, Janusz Krzysztofik wrote:
> > > > Both drivers use separate subsets of registers that belong to
the
> > OMAP1
> > > > MPU I/O device, but are used for controlling different sets of
I/O
> > pins.
> > > > The NAND driver reads/writes the folowing registers:
> > > > - OMAP_MPUIO_INPUT_LATCH,
> > > > - OMAP_MPUIO_OUTPUT,
> > > > - OMAP_MPUIO_IO_CNTL,
> > > > while the keypad driver - the following:
> > > > - OMAP_MPUIO_KBR_LATCH,
> > > > - OMAP_MPUIO_KBC,
> > > > - OMAP_MPUIO_KBD_MASKIT
> > > > - OMAP_MPUIO_GPIO_DEBOUNCING.
> > > > Both subsets are non-overlapping, and we rely on the drivers
being
> > free
> > > > of bugs and doing their job correctly, not stepping on each
others'
> > > > feet, I guess.
> > >
> > > First of all, I think this information should be in the commit
> > message.
> > > Also, some sort of comment in the driver code would be nice.
> > >
> > > If locking the memory region is too coarse approach, the should
have a
> > > small separate omap-specific MPUIO subsystem which will be used by
> > > drivers to access MPUIO?
> > >
> > > Another question - should request_mem_region() be also removed
from
> > the
> > > omap-gpio driver then? I think it is more sensible to put a
comment
> > > there that it is sharing MPIO with other drivers, instead of
having
> > an
> > > illusion of exclusive memory region ownership.
> > >
> > > But this is up to the OMAP community - I can take this patch to my
> > > l2-mtd tree if you get an ack from Tony or other OMAP guys.
> >
> > Tony,
> > Would I get your Ack for this fix if I extend the commit message as
Artem
> > suggested? If not, what do you think should be a correct way to fix
the
> > regression?
>
> Well how about adding some exported functions to
drivers/gpio/gpio_omap.c
> like omap_mpuio_latch?
>
> For the regression fix, if you guys want to do what Janusz is
suggesting,
> then assuming the patch description also contains some decent long
term
> plan to properly fix it:
>
> Acked-by: Tony Lindgren <[email protected]>
Thanks. Now that we know you prefer to keep the memory requested from
inside the gpio-omap, which I was about to suggest to drop back as an
alternative fix, I'll try to cook a new description for my patch, and
perhaps add a comment replacing the request_mem_region function removed
from the ams-delta NAND driver, in order to satisfy both yours and
Artem's comments in a few days.
Regards,
Janusz
A call to request_mem_region() has been introduced in the omap-gpio
driver recently (commit 96751fcbe5438e95514b025e9cee7a6d38038f40,
"gpio/omap: Use devm_ API and add request_mem_region"). This change
prevented the Amstrad Delta NAND driver, which was doing the same in
order to take control over OMAP MPU I/O lines that the NAND device hangs
off, from loading successfully.
The I/O lines and corresponding registers used by the NAND driver are a
subset of those used for the GPIO function. Then, to avoid run time
collisions, all MPUIO GPIO lines should be marked as requested while
initializing the NAND driver, and vice versa, a single MPUIO GPIO line
already requested before the NAND driver initialization is attempted
should prevent the NAND device from being started successfully.
There is another driver, omap-keypad, which also manipulates MPUIO
registers, but has never been calling request_mem_region() on startup,
so it's not affected by the change in the gpio-omap and works correctly.
It uses the depreciated omap_read/write functions for accessing MPUIO
registers. Unlike the NAND driver, these I/O lines and registers are
separate from those used by the GPIO driver. However, both register sets
are non-contiguous and overlapping, so it would be impractical to
request the two sets separately, one from the gpio-omap, the other form
the omap-keypad driver.
In order to solve all these issues correctly, a solution first suggested
by Artem Bityutskiy, then closer specified by Tony Lindgren while they
commented the initial version of this fix, should be implemented. The
gpio-omap driver should export a few functions which would allow the
other two drivers to access MPUIO registers in a safe manner instead of
trying to manage them in parallel to the GPIO driver. However, such a
big change, affecting 3 drivers all together, is not suitable for the rc
cycle, and should be prepared for the merge window. Then, an
alternative solution is proposed as a regression fix.
For the ams-delta NAND driver to initialize correctly in coexistence
with the changed GPIO driver, drop the request_mem_region() call from
the former, especially as this call is going to be removed while the
long-term solution is implemented.
Tested on Amstrad Delta.
Signed-off-by: Janusz Krzysztofik <[email protected]>
Acked-by: Tony Lindgren <[email protected]>
---
Artem, Tony,
I hope the changelog message is now good enough to make you satisfied,
and render the Tony's Ack valid.
Changes against initial version:
* a comment replacing the removed function call added,
* more details on the three drivers coexistance and possible interaction
provided,
* a hopefuly decent long-term plan to properly fix all identified issues
proposed.
drivers/mtd/nand/ams-delta.c | 16 ++++++----------
1 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/mtd/nand/ams-delta.c b/drivers/mtd/nand/ams-delta.c
index 7341695..358162a 100644
--- a/drivers/mtd/nand/ams-delta.c
+++ b/drivers/mtd/nand/ams-delta.c
@@ -212,18 +212,17 @@ static int __devinit ams_delta_init(struct platform_device *pdev)
/* Link the private data with the MTD structure */
ams_delta_mtd->priv = this;
- if (!request_mem_region(res->start, resource_size(res),
- dev_name(&pdev->dev))) {
- dev_err(&pdev->dev, "request_mem_region failed\n");
- err = -EBUSY;
- goto out_free;
- }
+ /*
+ * Don't try to request the memory region from here,
+ * it should have been already requested from the
+ * gpio-omap driver and requesting it again would fail.
+ */
io_base = ioremap(res->start, resource_size(res));
if (io_base == NULL) {
dev_err(&pdev->dev, "ioremap failed\n");
err = -EIO;
- goto out_release_io;
+ goto out_free;
}
this->priv = io_base;
@@ -271,8 +270,6 @@ out_gpio:
platform_set_drvdata(pdev, NULL);
gpio_free(AMS_DELTA_GPIO_PIN_NAND_RB);
iounmap(io_base);
-out_release_io:
- release_mem_region(res->start, resource_size(res));
out_free:
kfree(ams_delta_mtd);
out:
@@ -293,7 +290,6 @@ static int __devexit ams_delta_cleanup(struct platform_device *pdev)
gpio_free_array(_mandatory_gpio, ARRAY_SIZE(_mandatory_gpio));
gpio_free(AMS_DELTA_GPIO_PIN_NAND_RB);
iounmap(io_base);
- release_mem_region(res->start, resource_size(res));
/* Free the MTD device structure */
kfree(ams_delta_mtd);
--
1.7.3.4
On Mon, 2012-05-07 at 22:51 +0200, Janusz Krzysztofik wrote:
> A call to request_mem_region() has been introduced in the omap-gpio
> driver recently (commit 96751fcbe5438e95514b025e9cee7a6d38038f40,
> "gpio/omap: Use devm_ API and add request_mem_region"). This change
> prevented the Amstrad Delta NAND driver, which was doing the same in
> order to take control over OMAP MPU I/O lines that the NAND device hangs
> off, from loading successfully.
Aiaiai found out that your patch adds this gcc warning:
--------------------------------------------------------------------------------
Successfully built configuration "l2_omap1_defconfig,arm,arm-unknown-linux-gnueabi-", results:
--- before_patching.log
+++ after_patching.log
@@ @@
+drivers/mtd/nand/ams-delta.c: In function 'ams_delta_cleanup':
+drivers/mtd/nand/ams-delta.c:285:19: warning: unused variable 'res' [-Wunused-variable]
--------------------------------------------------------------------------------
--
Best Regards,
Artem Bityutskiy
On Tue, 2012-05-08 at 10:03 +0300, Artem Bityutskiy wrote:
> On Mon, 2012-05-07 at 22:51 +0200, Janusz Krzysztofik wrote:
> > A call to request_mem_region() has been introduced in the omap-gpio
> > driver recently (commit 96751fcbe5438e95514b025e9cee7a6d38038f40,
> > "gpio/omap: Use devm_ API and add request_mem_region"). This change
> > prevented the Amstrad Delta NAND driver, which was doing the same in
> > order to take control over OMAP MPU I/O lines that the NAND device hangs
> > off, from loading successfully.
>
> Aiaiai found out that your patch adds this gcc warning:
>
> --------------------------------------------------------------------------------
>
> Successfully built configuration "l2_omap1_defconfig,arm,arm-unknown-linux-gnueabi-", results:
>
> --- before_patching.log
> +++ after_patching.log
> @@ @@
> +drivers/mtd/nand/ams-delta.c: In function 'ams_delta_cleanup':
> +drivers/mtd/nand/ams-delta.c:285:19: warning: unused variable 'res' [-Wunused-variable]
>
> --------------------------------------------------------------------------------
But I've fixed this up and pushed to l2-mtd.git. From the commit message
I have an impression that you are not going to implement that longer
term plan. Dunno if Tony has a plan to force someone to do this by
blocking some changes which are not urgent fixes. Hmm? :-)
--
Best Regards,
Artem Bityutskiy
Dnia wtorek, 8 maja 2012 10:11:46 Artem Bityutskiy pisze:
> On Tue, 2012-05-08 at 10:03 +0300, Artem Bityutskiy wrote:
> > On Mon, 2012-05-07 at 22:51 +0200, Janusz Krzysztofik wrote:
> > > A call to request_mem_region() has been introduced in the omap-
gpio
> > > driver recently (commit 96751fcbe5438e95514b025e9cee7a6d38038f40,
> > > "gpio/omap: Use devm_ API and add request_mem_region"). This
change
> > > prevented the Amstrad Delta NAND driver, which was doing the same
in
> > > order to take control over OMAP MPU I/O lines that the NAND device
hangs
> > > off, from loading successfully.
> >
> > Aiaiai found out that your patch adds this gcc warning:
> >
> >
--------------------------------------------------------------------------------
> >
> > Successfully built configuration "l2_omap1_defconfig,arm,arm-unknown-
linux-gnueabi-", results:
> >
> > --- before_patching.log
> > +++ after_patching.log
> > @@ @@
> > +drivers/mtd/nand/ams-delta.c: In function 'ams_delta_cleanup':
> > +drivers/mtd/nand/ams-delta.c:285:19: warning: unused variable 'res'
[-Wunused-variable]
> >
> >
--------------------------------------------------------------------------------
>
> But I've fixed this up and pushed to l2-mtd.git.
Many thanks for this.
> From the commit message
> I have an impression that you are not going to implement that longer
> term plan.
I just didn't state 'I'll do it for the next merge window' because my
spare time resources are limited, and I've at least one set of changes
to the Amstrad Delta code still waiting on my todo list.
I'll try to implement that long term plan as my spare time permits.
Thanks,
Janusz