linux-kernel - Re: [PATCH v4 1/1] ucsi_ccg: Check DEV

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Date:   Wed, 12 Jan 2022 09:50:45 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Wayne Chang <waynec@...dia.com>
Cc:     gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, singhanc@...dia.com
Subject: Re: [PATCH v4 1/1] ucsi_ccg: Check DEV_INT bit only when starting
 CCG4

Hi,

On Wed, Jan 12, 2022 at 01:49:50PM +0800, Wayne Chang wrote:
> From: Sing-Han Chen <singhanc@...dia.com>
> 
> after driver sending the UCSI_START cmd, CCGx would
> clear Bit 0:Device Interrupt in the INTR_REG if CCGX
> reset successfully.
> 
> however, there might be a chance that other bits in
> INTR_REG are not cleared due to internal data queued
> in PPM and cause the driver thinks CCGx reset failed.
> 
> the commit checks bit 0 in INTR_REG and ignore other
> bits. ucsi driver would reset PPM later.
> 
> Fixes: 247c554a14aa ("usb: typec: ucsi: add support for Cypress CCGx")

So... no need to take this to the stable kernel releases?

> Signed-off-by: Sing-Han Chen <singhanc@...dia.com>
> Signed-off-by: Wayne Chang <waynec@...dia.com>
> ---

What has changed since v3 (and v2) - there is no patch changelog here?

In case this is new to you, you list those changes under that '---'
line so they don't become part of the permanent changelog:

https://docs.kernel.org/process/submitting-patches.html#the-canonical-patch-format

>  drivers/usb/typec/ucsi/ucsi_ccg.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c b/drivers/usb/typec/ucsi/ucsi_ccg.c
> index bff96d64dddf..6db7c8ddd51c 100644
> --- a/drivers/usb/typec/ucsi/ucsi_ccg.c
> +++ b/drivers/usb/typec/ucsi/ucsi_ccg.c
> @@ -325,7 +325,7 @@ static int ucsi_ccg_init(struct ucsi_ccg *uc)
>  		if (status < 0)
>  			return status;
>  
> -		if (!data)
> +		if (!(data & DEV_INT))
>  			return 0;
>  
>  		status = ccg_write(uc, CCGX_RAB_INTR_REG, &data, sizeof(data));

thanks,

-- 
heikki