linux-kernel - Re: [PATCH] extcon: sm5502: Reset registers during initialization

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Message-ID: <7432858f-3a22-b7f6-ec02-4e44dc9e71b5@samsung.com>
Date:   Fri, 11 Oct 2019 10:44:34 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Stephan Gerhold <stephan@...hold.net>,
        MyungJoo Ham <myungjoo.ham@...sung.com>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] extcon: sm5502: Reset registers during initialization

On 19. 10. 11. 오전 12:47, Stephan Gerhold wrote:
> On some devices (e.g. Samsung Galaxy A5 (2015)), the bootloader
> seems to keep interrupts enabled for SM5502 when booting Linux.
> Changing the cable state (i.e. plugging in a cable) - until the driver
> is loaded - will therefore produce an interrupt that is never read.
> 
> In this situation, the cable state will be stuck forever on the
> initial state because SM5502 stops sending interrupts.
> This can be avoided by clearing those pending interrupts after
> the driver has been loaded.
> 
> One way to do this is to reset all registers to default state
> by writing to SM5502_REG_RESET. This ensures that we start from
> a clean state, with all interrupts disabled.
> 
> Suggested-by: Chanwoo Choi <cw00.choi@...sung.com>
> Signed-off-by: Stephan Gerhold <stephan@...hold.net>
> ---
>  drivers/extcon/extcon-sm5502.c | 4 ++++
>  drivers/extcon/extcon-sm5502.h | 2 ++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/drivers/extcon/extcon-sm5502.c b/drivers/extcon/extcon-sm5502.c
> index dc43847ad2b0..b3d93baf4fc5 100644
> --- a/drivers/extcon/extcon-sm5502.c
> +++ b/drivers/extcon/extcon-sm5502.c
> @@ -65,6 +65,10 @@ struct sm5502_muic_info {
>  /* Default value of SM5502 register to bring up MUIC device. */
>  static struct reg_data sm5502_reg_data[] = {
>  	{
> +		.reg = SM5502_REG_RESET,
> +		.val = SM5502_REG_RESET_MASK,
> +		.invert = true,
> +	}, {
>  		.reg = SM5502_REG_CONTROL,
>  		.val = SM5502_REG_CONTROL_MASK_INT_MASK,
>  		.invert = false,
> diff --git a/drivers/extcon/extcon-sm5502.h b/drivers/extcon/extcon-sm5502.h
> index 9dbb634d213b..ce1f1ec310c4 100644
> --- a/drivers/extcon/extcon-sm5502.h
> +++ b/drivers/extcon/extcon-sm5502.h
> @@ -237,6 +237,8 @@ enum sm5502_reg {
>  #define DM_DP_SWITCH_UART			((DM_DP_CON_SWITCH_UART <<SM5502_REG_MANUAL_SW1_DP_SHIFT) \
>  						| (DM_DP_CON_SWITCH_UART <<SM5502_REG_MANUAL_SW1_DM_SHIFT))
>  
> +#define SM5502_REG_RESET_MASK			(0x1)
> +
>  /* SM5502 Interrupts */
>  enum sm5502_irq {
>  	/* INT1 */
> 

Applied it. Thanks.

When you send the patch on later, you better to specify the version
on patch title as following:
	[PATCH v2] extcon: sm5502: Reset registers during initialization

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics