[PATCH linux dev-5.10 06/35] ARM: dts: aspeed: rainier: Add leds that are off PCA9552

[Jacek Anaszewski]

Hi Vishwanatha,

On 4/26/21 7:59 AM, vishwanatha subbanna wrote:
> Joel,
> 
> With the experiments that I have done, I can not express LEDs with PCA955X_TYPE_LED predominantly because LEDs won’t
> retain states after the BMC reboot. I cooked a patch and tried but it does not work. I did an experiment where
> I put the patch and then did a reboot and saw that the LEDs were [OFF] in the very early stage of probe itself.
> 
>>From a9fe9e956c624c15a455b88cc05262358519a541 Mon Sep 17 00:00:00 2001
> From: Vishwanatha Subbanna <vishwa at linux.vnet.ibm.com>
> Date: Fri, 23 Apr 2021 06:57:56 -0500
> Subject: [PATCH 1/2] leds: pca955x: Add support for default-state
> 
> Signed-off-by: Vishwanatha Subbanna <vishwa at linux.vnet.ibm.com>
> ---
>   drivers/leds/leds-pca955x.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c
> index bf7ead4..987415b 100644
> --- a/drivers/leds/leds-pca955x.c
> +++ b/drivers/leds/leds-pca955x.c
> @@ -130,6 +130,7 @@ struct pca955x_led {
>   	char			name[32];
>   	u32			type;
>   	const char		*default_trigger;
> +	const char		*default_state;
>   };
>   
>   struct pca955x_platform_data {
> @@ -408,6 +409,8 @@ static int pca955x_gpio_direction_output(struct gpio_chip *gc,
>   		fwnode_property_read_u32(child, "type", &pdata->leds[reg].type);
>   		fwnode_property_read_string(child, "linux,default-trigger",
>   					&pdata->leds[reg].default_trigger);
> +		fwnode_property_read_string(child, "default-state",
> +					&pdata->leds[reg].default_state);
>   	}
>   
>   	pdata->num_leds = chip->bits;
> @@ -520,8 +523,13 @@ static int pca955x_probe(struct i2c_client *client,
>   			if (err)
>   				return err;
>   
> -			/* Turn off LED */
> -			err = pca955x_led_set(&pca955x_led->led_cdev, LED_OFF);
> +			/* If the default-state is "keep", don't change states */
> +			if (strcmp(pdata->leds[i].default_state, "keep")) {
> +				if (!strcmp(pdata->leds[i].default_state, "on"))
> +					err = pca955x_led_set(&pca955x_led->led_cdev, LED_ON);
> +				else
> +					err = pca955x_led_set(&pca955x_led->led_cdev, LED_OFF);
> +			}
>   			if (err)
>   				return err;
>   		}
> —
> 1.8.3.1
> 
> 
> For `leds-gpio`, Andrew had put a patch, but I don’t see how that can be mapped to PCA955X. https://github.com/torvalds/linux/commit/f5808ac158f2b16b686a3d3c0879c5d6048aba14
> 
> Jacek,
> 
> Please could you help me here ?.. I need to express LEDs as PCA955X_TYPE_LED and also retain states post BMC reboot.

If in your setup the LED controller loses power on reboot then there
is nothing you can do to retain the state.

-- 
Best regards,
Jacek Anaszewski