linux-kernel - Re: [PATCH v2 2/2] serial: 8250: Use BIT(x) for UART_{CAP,BUG}

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Date:   Wed, 19 May 2021 16:05:02 +0930
From:   "Andrew Jeffery" <andrew@...id.au>
To:     "Jiri Slaby" <jirislaby@...nel.org>, linux-serial@...r.kernel.org
Cc:     "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Joel Stanley" <joel@....id.au>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, openbmc@...ts.ozlabs.org,
        jenmin_yuan@...eedtech.com, "Ryan Chen" <ryan_chen@...eedtech.com>,
        "Milton Miller II" <miltonm@...ibm.com>
Subject: Re: [PATCH v2 2/2] serial: 8250: Use BIT(x) for UART_{CAP,BUG}_*



On Wed, 19 May 2021, at 16:02, Jiri Slaby wrote:
> On 19. 05. 21, 8:27, Andrew Jeffery wrote:
> > 
> > 
> > On Wed, 19 May 2021, at 15:44, Jiri Slaby wrote:
> >> On 19. 05. 21, 2:07, Andrew Jeffery wrote:
> >>> BIT(x) improves readability and safety with respect to shifts.
> >>>
> >>> Signed-off-by: Andrew Jeffery <andrew@...id.au>
> >>> ---
> >>>    drivers/tty/serial/8250/8250.h | 33 +++++++++++++++++----------------
> >>>    1 file changed, 17 insertions(+), 16 deletions(-)
> >>>
> >>> diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
> >>> index 34aa2714f3c9..4fbf1088fad8 100644
> >>> --- a/drivers/tty/serial/8250/8250.h
> >>> +++ b/drivers/tty/serial/8250/8250.h
> >>> @@ -7,6 +7,7 @@
> >>>     *  Copyright (C) 2001 Russell King.
> >>>     */
> >>>    
> >>> +#include <linux/bitops.h>
> >>>    #include <linux/serial_8250.h>
> >>>    #include <linux/serial_reg.h>
> >>>    #include <linux/dmaengine.h>
> >>> @@ -70,25 +71,25 @@ struct serial8250_config {
> >>>    	unsigned int	flags;
> >>>    };
> >>>    
> >>> -#define UART_CAP_FIFO	(1 << 8)	/* UART has FIFO */
> >>> -#define UART_CAP_EFR	(1 << 9)	/* UART has EFR */
> >>> -#define UART_CAP_SLEEP	(1 << 10)	/* UART has IER sleep */
> >>> -#define UART_CAP_AFE	(1 << 11)	/* MCR-based hw flow control */
> >>> -#define UART_CAP_UUE	(1 << 12)	/* UART needs IER bit 6 set (Xscale) */
> >>> -#define UART_CAP_RTOIE	(1 << 13)	/* UART needs IER bit 4 set (Xscale, Tegra) */
> >>> -#define UART_CAP_HFIFO	(1 << 14)	/* UART has a "hidden" FIFO */
> >>> -#define UART_CAP_RPM	(1 << 15)	/* Runtime PM is active while idle */
> >>> -#define UART_CAP_IRDA	(1 << 16)	/* UART supports IrDA line discipline */
> >>> -#define UART_CAP_MINI	(1 << 17)	/* Mini UART on BCM283X family lacks:
> >>> +#define UART_CAP_FIFO	BIT(8)	/* UART has FIFO */
> >>> +#define UART_CAP_EFR	BIT(9)	/* UART has EFR */
> >>> +#define UART_CAP_SLEEP	BIT(10)	/* UART has IER sleep */
> >>
> >>
> >> Perfect, except the include: BIT is not defined in bitops.h, but in
> >> bits.h (which includes vdso/bits.h). In fact, bitops.h includes bits.h
> >> too, but it's superfluous to include all those bitops.
> > 
> > Maybe the recommendation in the checkpatch documentation should be
> > fixed then?
> 
> +1 since:
> 
> commit 8bd9cb51daac89337295b6f037b0486911e1b408
> Author: Will Deacon <will@...nel.org>
> Date:   Tue Jun 19 13:53:08 2018 +0100
> 
>      locking/atomics, asm-generic: Move some macros from 
> <linux/bitops.h> to a new <linux/bits.h> file
> 
> So care to fix checkpatch too :)?

Yeah, I'll sort that out.

Andrew