Idea: regmap_config.use_single_rw -> use_single_read, use_single_write

Idea: regmap_config.use_single_rw -> use_single_read, use_single_write

[David Frey]

Hi,

I just want to float an idea and see if it gets any support.

In struct regmap_config, there is a member "bool use_single_rw" which is
documented as follows:

"If set, converts the bulk read and write operations into a series of
single read and write operations. This is useful for device that does
not support bulk read and write."

My idea is to split this into:
	bool use_single_read;
	bool use_single_write;

I think this would be useful because at least one device that I'm using
(Bosch bmi160 IMU) supports bulk reads, but not bulk writes.  It would
be convenient to be able to use regmap_bulk_read and regmap_bulk_write
and have only regmap_bulk_write split the writes apart.  This change
would also support the case where a device supports bulk writes, but not
bulk reads.  I don't know of such a device, but I haven't made any
attempt to find one.

What do you think?

David Frey

Re: Idea: regmap_config.use_single_rw -> use_single_read, use_single_write

[David Frey]

On 8/29/2018 10:35 AM, David Frey wrote:
> Hi,
> 
> I just want to float an idea and see if it gets any support.
> 
> In struct regmap_config, there is a member "bool use_single_rw" which is
> documented as follows:
> 
> "If set, converts the bulk read and write operations into a series of
> single read and write operations. This is useful for device that does
> not support bulk read and write."
> 
> My idea is to split this into:
> 	bool use_single_read;
> 	bool use_single_write;
> 
> I think this would be useful because at least one device that I'm using
> (Bosch bmi160 IMU) supports bulk reads, but not bulk writes.  It would
> be convenient to be able to use regmap_bulk_read and regmap_bulk_write
> and have only regmap_bulk_write split the writes apart.  This change
> would also support the case where a device supports bulk writes, but not
> bulk reads.  I don't know of such a device, but I haven't made any
> attempt to find one.
> 
> What do you think?
> 
> David Frey

I realized after I sent this that this is a regmap change and thus might
be out of scope for discussion on the linux-iio mailing list.  Is there
somewhere more appropriate to post this to?

Thanks,
David

Re: Idea: regmap_config.use_single_rw -> use_single_read, use_single_write

[Himanshu Jha]

On Fri, Aug 31, 2018 at 07:55:36AM -0700, David Frey wrote:
> On 8/29/2018 10:35 AM, David Frey wrote:
> > Hi,
> > 
> > I just want to float an idea and see if it gets any support.
> > 
> > In struct regmap_config, there is a member "bool use_single_rw" which is
> > documented as follows:
> > 
> > "If set, converts the bulk read and write operations into a series of
> > single read and write operations. This is useful for device that does
> > not support bulk read and write."
> > 
> > My idea is to split this into:
> > 	bool use_single_read;
> > 	bool use_single_write;
> > 
> > I think this would be useful because at least one device that I'm using
> > (Bosch bmi160 IMU) supports bulk reads, but not bulk writes.  It would
> > be convenient to be able to use regmap_bulk_read and regmap_bulk_write
> > and have only regmap_bulk_write split the writes apart.  This change
> > would also support the case where a device supports bulk writes, but not
> > bulk reads.  I don't know of such a device, but I haven't made any
> > attempt to find one.
> > 
> > What do you think?
> > 
> > David Frey
> 
> I realized after I sent this that this is a regmap change and thus might
> be out of scope for discussion on the linux-iio mailing list.  Is there
> somewhere more appropriate to post this to?

himanshu@himanshu-Vostro-3559:~/linux-next$ ./scripts/get_maintainer.pl  include/linux/regmap.h
Mark Brown <broonie@kernel.org> (supporter:REGISTER MAP ABSTRACTION)
linux-kernel@vger.kernel.org (open list:REGISTER MAP ABSTRACTION)



Thanks
-- 
Himanshu Jha
Undergraduate Student
Department of Electronics & Communication
Guru Tegh Bahadur Institute of Technology

Re: Idea: regmap_config.use_single_rw -> use_single_read, use_single_write

[Himanshu Jha]

On Fri, Aug 31, 2018 at 10:39:07PM +0530, Himanshu Jha wrote:
> On Fri, Aug 31, 2018 at 07:55:36AM -0700, David Frey wrote:
> > On 8/29/2018 10:35 AM, David Frey wrote:
> > > Hi,
> > > 
> > > I just want to float an idea and see if it gets any support.
> > > 
> > > In struct regmap_config, there is a member "bool use_single_rw" which is
> > > documented as follows:
> > > 
> > > "If set, converts the bulk read and write operations into a series of
> > > single read and write operations. This is useful for device that does
> > > not support bulk read and write."
> > > 
> > > My idea is to split this into:
> > > 	bool use_single_read;
> > > 	bool use_single_write;
> > > 
> > > I think this would be useful because at least one device that I'm using
> > > (Bosch bmi160 IMU) supports bulk reads, but not bulk writes.  It would
> > > be convenient to be able to use regmap_bulk_read and regmap_bulk_write
> > > and have only regmap_bulk_write split the writes apart.  This change
> > > would also support the case where a device supports bulk writes, but not
> > > bulk reads.  I don't know of such a device, but I haven't made any
> > > attempt to find one.
> > > 
> > > What do you think?

Btw, if device doesn't support a bulk write and instead only supports a bulk
read as we see in BMI160, wouldn't the following suffice the problem:

	.use_single_rw = true,
	.can_multi_write = false,  // or probably not setting it up(clear)

 313  * @can_multi_write: If set, the device supports the multi write mode of bulk
 314  *                   write operations, if clear multi write requests will be
 315  *                   split into individual write operations



Thanks
-- 
Himanshu Jha
Undergraduate Student
Department of Electronics & Communication
Guru Tegh Bahadur Institute of Technology

Re: Idea: regmap_config.use_single_rw -> use_single_read, use_single_write

[David Frey]

On 8/31/2018 10:20 AM, Himanshu Jha wrote:
> On Fri, Aug 31, 2018 at 10:39:07PM +0530, Himanshu Jha wrote:
>> On Fri, Aug 31, 2018 at 07:55:36AM -0700, David Frey wrote:
>>> On 8/29/2018 10:35 AM, David Frey wrote:
>>>> Hi,
>>>>
>>>> I just want to float an idea and see if it gets any support.
>>>>
>>>> In struct regmap_config, there is a member "bool use_single_rw" which is
>>>> documented as follows:
>>>>
>>>> "If set, converts the bulk read and write operations into a series of
>>>> single read and write operations. This is useful for device that does
>>>> not support bulk read and write."
>>>>
>>>> My idea is to split this into:
>>>> 	bool use_single_read;
>>>> 	bool use_single_write;
>>>>
>>>> I think this would be useful because at least one device that I'm using
>>>> (Bosch bmi160 IMU) supports bulk reads, but not bulk writes.  It would
>>>> be convenient to be able to use regmap_bulk_read and regmap_bulk_write
>>>> and have only regmap_bulk_write split the writes apart.  This change
>>>> would also support the case where a device supports bulk writes, but not
>>>> bulk reads.  I don't know of such a device, but I haven't made any
>>>> attempt to find one.
>>>>
>>>> What do you think?
> 
> Btw, if device doesn't support a bulk write and instead only supports a bulk
> read as we see in BMI160, wouldn't the following suffice the problem:
> 
> 	.use_single_rw = true,
> 	.can_multi_write = false,  // or probably not setting it up(clear)
> 
>  313  * @can_multi_write: If set, the device supports the multi write mode of bulk
>  314  *                   write operations, if clear multi write requests will be
>  315  *                   split into individual write operations

I don't think the can_multi_write flag is relevant here.  Bulk writes
have the form: {regN, dataN, dataN+1, dataN+2, ...}.  Multi-write is
used by regmap_multi_reg_write() and is this form: {regaA, dataA, regF,
dataF, regC, dataC, ...}.