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

Lee Jones
2015-05-13T12:10:46Z

On Wed, 13 May 2015, Javier Martinez Canillas wrote:

> 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.

Yes, you're absolutely right. You passed the test. ;)

Acked-by: Lee Jones <lee.jones@linaro.org>

> >> + 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;

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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