linux-kernel - Re: [PATCH v4 3/3] tty: serial: samsung: Fix serial rx on Apple A7-A9

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Message-ID: <fcfdef6d00e1f5084c85191ffa43e9756ddc0325.camel@samsung.com>
Date: Tue, 10 Sep 2024 13:15:52 +0900
From: Kwanghoon Son <k.son@...sung.com>
To: Nick Chan <towinchenmi@...il.com>, Krzysztof Kozlowski
	<krzk@...nel.org>,  Alim Akhtar <alim.akhtar@...sung.com>, Greg
	Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby
	<jirislaby@...nel.org>, linux-arm-kernel@...ts.infradead.org, 
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-serial@...r.kernel.org
Cc: asahi@...ts.linux.dev
Subject: Re: [PATCH v4 3/3] tty: serial: samsung: Fix serial rx on Apple
 A7-A9

On Tue, 2024-09-10 at 10:59 +0800, Nick Chan wrote:
> 
> On 10/9/2024 09:59, Kwanghoon Son wrote:
> > On Mon, 2024-09-09 at 17:51 +0800, Nick Chan wrote:
> > > 
> > > On 9/9/2024 17:43, Kwanghoon Son wrote:
> > > > On Mon, 2024-09-09 at 16:37 +0800, Nick Chan wrote:
> > > > > Apple's older A7-A9 SoCs seems to use bit 3 in UTRSTAT as RXTO, which is
> > > > > enabled by bit 11 in UCON.
> > > > > 
> > > > > Access these bits in addition to the original RXTO and RXTO enable bits,
> > > > > to allow serial rx to function on A7-A9 SoCs. This change does not
> > > > > appear to affect the A10 SoC and up.
> > > > > 
> > > > > Signed-off-by: Nick Chan <towinchenmi@...il.com>
> > > > > 
> > > > 
> > > > [snip]
> > > > 
> > > > > diff --git a/include/linux/serial_s3c.h b/include/linux/serial_s3c.h
> > > > > index 1e8686695487..964a4fbf2626 100644
> > > > > --- a/include/linux/serial_s3c.h
> > > > > +++ b/include/linux/serial_s3c.h
> > > > > @@ -246,24 +246,28 @@
> > > > >  				 S5PV210_UFCON_TXTRIG4 |	\
> > > > >  				 S5PV210_UFCON_RXTRIG4)
> > > > >  
> > > > > -#define APPLE_S5L_UCON_RXTO_ENA		9
> > > > > -#define APPLE_S5L_UCON_RXTHRESH_ENA	12
> > > > > -#define APPLE_S5L_UCON_TXTHRESH_ENA	13
> > > > > -#define APPLE_S5L_UCON_RXTO_ENA_MSK	BIT(APPLE_S5L_UCON_RXTO_ENA)
> > > > > -#define APPLE_S5L_UCON_RXTHRESH_ENA_MSK	BIT(APPLE_S5L_UCON_RXTHRESH_ENA)
> > > > > -#define APPLE_S5L_UCON_TXTHRESH_ENA_MSK	BIT(APPLE_S5L_UCON_TXTHRESH_ENA)
> > > > > +#define APPLE_S5L_UCON_RXTO_ENA			9
> > > > > +#define APPLE_S5L_UCON_RXTO_LEGACY_ENA		11
> > > > > +#define APPLE_S5L_UCON_RXTHRESH_ENA		12
> > > > > +#define APPLE_S5L_UCON_TXTHRESH_ENA		13
> > > > > +#define APPLE_S5L_UCON_RXTO_ENA_MSK		BIT(APPLE_S5L_UCON_RXTO_ENA)
> > > > > +#define APPLE_S5L_UCON_RXTO_LEGACY_ENA_MSK	BIT(APPLE_S5L_UCON_RXTO_LEGACY_ENA)
> > > > > +#define APPLE_S5L_UCON_RXTHRESH_ENA_MSK		BIT(APPLE_S5L_UCON_RXTHRESH_ENA)
> > > > > +#define APPLE_S5L_UCON_TXTHRESH_ENA_MSK		BIT(APPLE_S5L_UCON_TXTHRESH_ENA)
> > > > 
> > > > Small thing, but other diff is not needed except
> > > > APPLE_S5L_UCON_RXTO_LEGACY_ENA.
> > > > 
> > > > Kwang.
> > > The other diffs are there to keep everything aligned, it looks like a
> > > jumbled mess here in the email, but in an editor like nano it is all
> > > aligned, before or after this series.
> > 
> > I know why you did. But still there is way keep aligned and only one
> > line added. 
> > 
> > you just added one more tab to other lines.
> > If one tab with APPLE_S5L_UCON_RXTO_LEGACY_ENA, then everything will
> > fine.
> > 
> > I think less changes better when see git show or blame.
> While as you said, APPLE_S5L_UCON_RXTO_LEGACY_ENA would be fine,
> APPLE_S5L_UCON_RXTO_LEGACY_ENA_MSK is too long for that to be aligned, see
> below without +, - or > distorting everything.
> 
> Before:
> #define APPLE_S5L_UCON_RXTO_ENA		9
> #define APPLE_S5L_UCON_RXTHRESH_ENA	12
> #define APPLE_S5L_UCON_TXTHRESH_ENA	13
> #define APPLE_S5L_UCON_RXTO_ENA_MSK	(1 << APPLE_S5L_UCON_RXTO_ENA)
> #define APPLE_S5L_UCON_RXTHRESH_ENA_MSK	(1 << APPLE_S5L_UCON_RXTHRESH_ENA)
> #define APPLE_S5L_UCON_TXTHRESH_ENA_MSK	(1 << APPLE_S5L_UCON_TXTHRESH_ENA)
> 
> Patch 1:
> #define APPLE_S5L_UCON_RXTO_ENA		9
> #define APPLE_S5L_UCON_RXTHRESH_ENA	12
> #define APPLE_S5L_UCON_TXTHRESH_ENA	13
> #define APPLE_S5L_UCON_RXTO_ENA_MSK	BIT(APPLE_S5L_UCON_RXTO_ENA)
> #define APPLE_S5L_UCON_RXTHRESH_ENA_MSK	BIT(APPLE_S5L_UCON_RXTHRESH_ENA)
> #define APPLE_S5L_UCON_TXTHRESH_ENA_MSK	BIT(APPLE_S5L_UCON_TXTHRESH_ENA)
> 
> After:
> #define APPLE_S5L_UCON_RXTO_ENA			9
> #define APPLE_S5L_UCON_RXTO_LEGACY_ENA		11
> #define APPLE_S5L_UCON_RXTHRESH_ENA		12
> #define APPLE_S5L_UCON_TXTHRESH_ENA		13
> #define APPLE_S5L_UCON_RXTO_ENA_MSK		BIT(APPLE_S5L_UCON_RXTO_ENA)
> #define APPLE_S5L_UCON_RXTO_LEGACY_ENA_MSK
> BIT(APPLE_S5L_UCON_RXTO_LEGACY_ENA)
> #define APPLE_S5L_UCON_RXTHRESH_ENA_MSK		BIT(APPLE_S5L_UCON_RXTHRESH_ENA)
> #define APPLE_S5L_UCON_TXTHRESH_ENA_MSK		BIT(APPLE_S5L_UCON_TXTHRESH_ENA)
> 

Okay I got it.
Thanks for check!

Kwang.

> > 
> > Best regards,
> > Kwang.
> > 
> > > 
> > > > 
> > > > >  
> > > > >  #define APPLE_S5L_UCON_DEFAULT		(S3C2410_UCON_TXIRQMODE | \
> > > > >  					 S3C2410_UCON_RXIRQMODE | \
> > > > >  					 S3C2410_UCON_RXFIFO_TOI)
> > > > >  #define APPLE_S5L_UCON_MASK		(APPLE_S5L_UCON_RXTO_ENA_MSK | \
> > > > > +					 APPLE_S5L_UCON_RXTO_LEGACY_ENA_MSK | \
> > > > >  					 APPLE_S5L_UCON_RXTHRESH_ENA_MSK | \
> > > > >  					 APPLE_S5L_UCON_TXTHRESH_ENA_MSK)
> > > > >  
> > > > > +#define APPLE_S5L_UTRSTAT_RXTO_LEGACY	BIT(3)
> > > > >  #define APPLE_S5L_UTRSTAT_RXTHRESH	BIT(4)
> > > > >  #define APPLE_S5L_UTRSTAT_TXTHRESH	BIT(5)
> > > > >  #define APPLE_S5L_UTRSTAT_RXTO		BIT(9)
> > > > > -#define APPLE_S5L_UTRSTAT_ALL_FLAGS	(0x3f0)
> > > > > +#define APPLE_S5L_UTRSTAT_ALL_FLAGS	(0x3f8)
> > > > >  
> > > > >  #ifndef __ASSEMBLY__
> > > > >  
> > > > 
> > > 
> > > Nick Chan
> > 
> 
> Nick Chan
>