Re: [PATCH/RFC v9 04/19] mfd: max77693: adjust max77693_led_platform_data

From: Jacek Anaszewski
Date: Tue Dec 09 2014 - 09:02:16 EST


On 12/09/2014 02:50 PM, Lee Jones wrote:
On Tue, 09 Dec 2014, Jacek Anaszewski wrote:

On 12/09/2014 11:04 AM, Lee Jones wrote:
On Tue, 09 Dec 2014, Jacek Anaszewski wrote:

On 12/09/2014 09:50 AM, Lee Jones wrote:
On Wed, 03 Dec 2014, Jacek Anaszewski wrote:

Add "label" array for Device Tree strings with the name of a LED device
and make flash_timeout a two element array, for caching the sub-led
related flash timeout. Added is also an array for caching pointers to the
sub-nodes representing sub-leds.

Signed-off-by: Jacek Anaszewski <j.anaszewski@xxxxxxxxxxx>
Acked-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Cc: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
Cc: Lee Jones <lee.jones@xxxxxxxxxx>
---
include/linux/mfd/max77693.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/mfd/max77693.h b/include/linux/mfd/max77693.h
index f0b6585..c80ee99 100644
--- a/include/linux/mfd/max77693.h
+++ b/include/linux/mfd/max77693.h
@@ -88,16 +88,18 @@ enum max77693_led_boost_mode {
};

struct max77693_led_platform_data {
+ const char *label[2];
u32 fleds[2];
u32 iout_torch[2];for_each_available_child_of_node
u32 iout_flash[2];
u32 trigger[2];
u32 trigger_type[2];
+ u32 flash_timeout[2];
u32 num_leds;
u32 boost_mode;
- u32 flash_timeout;
u32 boost_vout;
u32 low_vsys;
+ struct device_node *sub_nodes[2];

I haven't seen anyone do this before. Why can't you use the provided
OF functions to traverse through your tree?

I use for_each_available_child_of_node when parsing DT node, but I
need to cache the pointer to sub-node to be able to use it later
when it needs to be passed to V4L2 sub-device which is then
asynchronously matched by the phandle to sub-node.

If it is not well seen to cache it in the platform data then
I will find different way to accomplish this.

I haven't seen the end-driver for this, but why can't you use that
device's of_node pointer?

Maybe it is indeed a good idea. I could pass the of_node pointer
and the sub-led identifier to the V4L2 sub-device and there look
for the sub-node containing relevant identifier. The downside
would be only that for_each_available_child_of_node would
have to be called twice - in the led driver and in the V4L2 sub-device.
I think that we can live with it.

Are the LED and V4L2 drivers children of this MFD? If so, you can use
the of_compatible attribute in struct mfd_cell to populate the each
child's of_node dynamically i.e. the MFD core will do that for you.


V4L2 driver wraps LED driver. This way the LED device can be
controlled with use of two interfaces - LED subsystem sysfs
and V4L2 Flash. This is the aim of the whole patch set.

I've thought it over again and it seems that I will need to cache
somewhere these sub_nodes pointers. They have to be easily accessible
for the V4L2 sub-device as it can be asynchronously registered
or unregistered within V4L2 media device. Sub-devices are matched
basing on the sub-node phandle.

Best Regards,
Jacek Anaszewski
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