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Subject: Re: [PATCH v2 2/2] serial: 8250: Use BIT(x) for UART_{CAP,BUG}_*
To:     Andrew Jeffery <andrew@aj.id.au>, linux-serial@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Joel Stanley <joel@jms.id.au>, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-aspeed@lists.ozlabs.org, openbmc@lists.ozlabs.org,
        jenmin_yuan@aspeedtech.com, Ryan Chen <ryan_chen@aspeedtech.com>,
        Milton Miller II <miltonm@us.ibm.com>
References: <20210519000704.3661773-1-andrew@aj.id.au>
 <20210519000704.3661773-3-andrew@aj.id.au>
 <56ec152a-560b-1eed-97e2-c12e4fed171a@kernel.org>
 <2bb7dfc4-a20e-4e3e-8fa5-74ff264c4e44@www.fastmail.com>
From:   Jiri Slaby <jirislaby@kernel.org>
Message-ID: <a67f0c95-7708-569f-099b-db9e2ad9616d@kernel.org>
Date:   Wed, 19 May 2021 08:32:13 +0200
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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@aj.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@kernel.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 :)?

thanks,
-- 
js
suse labs