[PATCH] platform: fall-back to driver name check if there is no id found

[PATCH] platform: fall-back to driver name check if there is no id found

[Andy Shevchenko]

Some of the platform devices rely on the name of their driver to match with. In
the current implementation, if platform id table is needed, they have to add
the name to the platform id table which sounds alogical. The patch adjustes the
logic of the id table matching to make sure we will fall-back to match by the
driver name. This will make it similar to the DT or ACPI cases.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reported-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Eric Miao <eric.miao@marvell.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
---
 drivers/base/platform.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index c0b8df3..452ba4b 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -732,8 +732,8 @@ static int platform_match(struct device *dev, struct device_driver *drv)
 		return 1;
 
 	/* Then try to match against the id table */
-	if (pdrv->id_table)
-		return platform_match_id(pdrv->id_table, pdev) != NULL;
+	if (pdrv->id_table && platform_match_id(pdrv->id_table, pdev))
+		return 1;
 
 	/* fall-back to driver name match */
 	return (strcmp(pdev->name, drv->name) == 0);
-- 
1.7.10.4

RE: [PATCH] platform: fall-back to driver name check if there is no id found

[Hein Tibosch]

Hi Andy, Mika,

On 8 Feb 2013, Andy Shevchenko wrote:

> Some of the platform devices rely on the name of their driver to match with. In
> the current implementation, if platform id table is needed, they have to add
> the name to the platform id table which sounds alogical. The patch adjustes the
> logic of the id table matching to make sure we will fall-back to match by the
> driver name. This will make it similar to the DT or ACPI cases.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Reported-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Cc: Eric Miao <eric.miao@xxxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxx>
> ---
>  drivers/base/platform.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index c0b8df3..452ba4b 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -732,8 +732,8 @@ static int platform_match(struct device *dev, struct device_driver *drv)
>  		return 1;
>  
>  	/* Then try to match against the id table */
> -	if (pdrv->id_table)
> -		return platform_match_id(pdrv->id_table, pdev) != NULL;
> +	if (pdrv->id_table && platform_match_id(pdrv->id_table, pdev))
> +		return 1;
>  
>  	/* fall-back to driver name match */
>  	return (strcmp(pdev->name, drv->name) == 0);

When I upgraded an avr32 system from 3.8 to a recent next release, I found it was
broken: DMA was not available because the dw_dma driver did not get probed anymore.

The dw_dma driver does have a id_table, but the boards in arch/avr32 are still expecting
driver identification by name.

As long as we want to support this simple identification-by-name, I'd say Andy's patch
should get quickly into stable release.


Hein

Re: [PATCH] platform: fall-back to driver name check if there is no id found

[Eric Miao]

On Fri, Apr 19, 2013 at 8:35 PM, Hein Tibosch <hein_tibosch@yahoo.es> wrote:
> Hi Andy, Mika,
>
> On 8 Feb 2013, Andy Shevchenko wrote:
>
>> Some of the platform devices rely on the name of their driver to match with. In
>> the current implementation, if platform id table is needed, they have to add
>> the name to the platform id table which sounds alogical. The patch adjustes the
>> logic of the id table matching to make sure we will fall-back to match by the
>> driver name. This will make it similar to the DT or ACPI cases.
>>
>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
>> Reported-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
>> Cc: Eric Miao <eric.miao@xxxxxxxxxxx>
>> Cc: Greg Kroah-Hartman <gregkh@xxxxxxx>
>> ---
>>  drivers/base/platform.c |    4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
>> index c0b8df3..452ba4b 100644
>> --- a/drivers/base/platform.c
>> +++ b/drivers/base/platform.c
>> @@ -732,8 +732,8 @@ static int platform_match(struct device *dev, struct device_driver *drv)
>>               return 1;
>>
>>       /* Then try to match against the id table */
>> -     if (pdrv->id_table)
>> -             return platform_match_id(pdrv->id_table, pdev) != NULL;
>> +     if (pdrv->id_table && platform_match_id(pdrv->id_table, pdev))
>> +             return 1;
>>
>>       /* fall-back to driver name match */
>>       return (strcmp(pdev->name, drv->name) == 0);
>
> When I upgraded an avr32 system from 3.8 to a recent next release, I found it was
> broken: DMA was not available because the dw_dma driver did not get probed anymore.
>
> The dw_dma driver does have a id_table, but the boards in arch/avr32 are still expecting
> driver identification by name.

I think this is a different philosophy here. I'm actually fine with either. The
questions are really:

1. will it be a bit inconsistent if the driver is using id_table,
while the device
is still using a legacy way?

2. instead of introducing a different logic in the platform driver core code,
is it possible this could be fixed at the board level?

>
> As long as we want to support this simple identification-by-name, I'd say Andy's patch
> should get quickly into stable release.

Re: [PATCH] platform: fall-back to driver name check if there is no id found

[Eric Miao]

On Fri, Apr 19, 2013 at 8:35 PM, Hein Tibosch <hein_tibosch@yahoo.es> wrote:
> Hi Andy, Mika,
>
> On 8 Feb 2013, Andy Shevchenko wrote:
>
>> Some of the platform devices rely on the name of their driver to match with. In
>> the current implementation, if platform id table is needed, they have to add
>> the name to the platform id table which sounds alogical. The patch adjustes the
>> logic of the id table matching to make sure we will fall-back to match by the
>> driver name. This will make it similar to the DT or ACPI cases.
>>
>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
>> Reported-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
>> Cc: Eric Miao <eric.miao@xxxxxxxxxxx>
>> Cc: Greg Kroah-Hartman <gregkh@xxxxxxx>
>> ---
>>  drivers/base/platform.c |    4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
>> index c0b8df3..452ba4b 100644
>> --- a/drivers/base/platform.c
>> +++ b/drivers/base/platform.c
>> @@ -732,8 +732,8 @@ static int platform_match(struct device *dev, struct device_driver *drv)
>>               return 1;
>>
>>       /* Then try to match against the id table */
>> -     if (pdrv->id_table)
>> -             return platform_match_id(pdrv->id_table, pdev) != NULL;
>> +     if (pdrv->id_table && platform_match_id(pdrv->id_table, pdev))
>> +             return 1;
>>
>>       /* fall-back to driver name match */
>>       return (strcmp(pdev->name, drv->name) == 0);
>
> When I upgraded an avr32 system from 3.8 to a recent next release, I found it was
> broken: DMA was not available because the dw_dma driver did not get probed anymore.
>
> The dw_dma driver does have a id_table, but the boards in arch/avr32 are still expecting
> driver identification by name.

I think this is a different philosophy here. I'm actually fine with either. The
questions are really:

1. will it be a bit inconsistent if the driver is using id_table,
while the device
is still using a legacy way?

2. instead of introducing a different logic in the platform driver core code,
is it possible this could be fixed at the board level?

>
> As long as we want to support this simple identification-by-name, I'd say Andy's patch
> should get quickly into stable release.

Re: [PATCH] platform: fall-back to driver name check if there is no id found

[Andy Shevchenko]

On Fri, 2013-04-19 at 21:20 +0800, Eric Miao wrote: 
> On Fri, Apr 19, 2013 at 8:35 PM, Hein Tibosch <hein_tibosch@yahoo.es> wrote:
> > Hi Andy, Mika,
> >
> > On 8 Feb 2013, Andy Shevchenko wrote:
> >
> >> Some of the platform devices rely on the name of their driver to match with. In
> >> the current implementation, if platform id table is needed, they have to add
> >> the name to the platform id table which sounds alogical. The patch adjustes the
> >> logic of the id table matching to make sure we will fall-back to match by the
> >> driver name. This will make it similar to the DT or ACPI cases.
> >>
> >> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> >> Reported-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> >> Cc: Eric Miao <eric.miao@xxxxxxxxxxx>
> >> Cc: Greg Kroah-Hartman <gregkh@xxxxxxx>
> >> ---
> >>  drivers/base/platform.c |    4 ++--
> >>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> >> index c0b8df3..452ba4b 100644
> >> --- a/drivers/base/platform.c
> >> +++ b/drivers/base/platform.c
> >> @@ -732,8 +732,8 @@ static int platform_match(struct device *dev, struct device_driver *drv)
> >>               return 1;
> >>
> >>       /* Then try to match against the id table */
> >> -     if (pdrv->id_table)
> >> -             return platform_match_id(pdrv->id_table, pdev) != NULL;
> >> +     if (pdrv->id_table && platform_match_id(pdrv->id_table, pdev))
> >> +             return 1;
> >>
> >>       /* fall-back to driver name match */
> >>       return (strcmp(pdev->name, drv->name) == 0);
> >
> > When I upgraded an avr32 system from 3.8 to a recent next release, I found it was
> > broken: DMA was not available because the dw_dma driver did not get probed anymore.
> >
> > The dw_dma driver does have a id_table, but the boards in arch/avr32 are still expecting
> > driver identification by name.
> 
> I think this is a different philosophy here. I'm actually fine with either. The
> questions are really:
> 
> 1. will it be a bit inconsistent if the driver is using id_table,
> while the device
> is still using a legacy way?

Legacy way may be considered as a fall-back.

> 2. instead of introducing a different logic in the platform driver core code,
> is it possible this could be fixed at the board level?

It might be fixed in the driver, though I think that is ugly approach,
by adding name of the driver into its id_table.

P.S. There are actually a few drivers in current mainline that uses
mentioned approach, but with this patch it will be not needed anymore.

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy