Re: [PATCH v2 03/10] mfd: cros_ec: Instantiate sub-devices from device tree

Javier Martinez Canillas
2015-05-13T11:43:55Z

Hello Lee,

On 05/13/2015 01:32 PM, Lee Jones wrote:
> On Sat, 09 May 2015, Javier Martinez Canillas wrote:
>
>> From: Todd Broch <tbroch@chromium.org>
>>
>> If the EC device tree node has sub-nodes, try to instantiate them as
>> MFD sub-devices. We can configure the EC features provided by the board.
>>
>> Signed-off-by: Todd Broch <tbroch@chromium.org>
>> Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
>> Tested-by: Heiko Stuebner <heiko@sntech.de>
>> Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
>> Tested-by: Gwendal Grignou <gwendal@chromium.org>
>> ---
>>
>> Changes since v1:
>> - Added Heiko Stuebner and Gwendal Grignou Tested-by tag
>> - Added Gwendal Grignou Reviewed-by tag
>> - Use automatic device ID instead of 1 as suggested by Lee Jones
>> - Remove #ifdeffery and check for of_node to register sub-devices
>> Suggested by Lee Jones
>> ---
>> drivers/mfd/cros_ec.c | 22 +++++++++++-----------
>> 1 file changed, 11 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
>> index c4aecc6f8373..1574a9352a6d 100644
>> --- a/drivers/mfd/cros_ec.c
>> +++ b/drivers/mfd/cros_ec.c
>> @@ -17,6 +17,7 @@
>> * battery charging and regulator control, firmware update.
>> */
>>
>> +#include <linux/of_platform.h>
>> #include <linux/interrupt.h>
>> #include <linux/slab.h>
>> #include <linux/module.h>
>> @@ -109,18 +110,8 @@ EXPORT_SYMBOL(cros_ec_cmd_xfer);
>>
>> static const struct mfd_cell cros_devs[] = {
>> {
>> - .name = "cros-ec-keyb",
>> - .id = 1,
>> - .of_compatible = "google,cros-ec-keyb",
>> - },
>> - {
>> - .name = "cros-ec-i2c-tunnel",
>> - .id = 2,
>> - .of_compatible = "google,cros-ec-i2c-tunnel",
>> - },
>> - {
>> .name = "cros-ec-ctl",
>> - .id = 3,
>> + .id = PLATFORM_DEVID_AUTO,
>> },
>> };
>>
>> @@ -150,6 +141,15 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
>> return err;
>> }
>>
>> + if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
>
> You don't need to check for OF. of_node will be NULL if OF isn't
> enabled.
>

Yes, you don't need it but IS_ENABLED(CONFIG_OF) causes the check to be
optimized away by the compiler if CONFIG_OF is not enabled AFAIK.

Without the IS_ENABLED(CONFIG_OF) check, this becomes a pointless pointer
check that will always evaluate to false on systems without CONFIG_OF
since as you said of_node will be present when CONFIG_OF is not enabled.
But the compiler has no way to know it will always be NULL to optimize it
away AFAICT.

>> + err = of_platform_populate(dev->of_node, NULL, NULL, dev);
>> + if (err) {
>> + mfd_remove_devices(dev);
>> + dev_err(dev, "Failed to register sub-devices\n");
>> + return err;
>> + }
>> + }
>> +
>> dev_info(dev, "Chrome EC device registered\n");
>>
>> return 0;
>

Best regards,
Javier