linux-kernel - Re: [PATCH 11/32] parport_pc: add 16-bit and 8-bit fast EPP transfer flags

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Message-ID: <6933a0fe-012d-d0e4-78e5-e651ab5f80a0@omp.ru>
Date:   Sat, 11 Mar 2023 23:31:47 +0300
From:   Sergey Shtylyov <s.shtylyov@....ru>
To:     Ondrej Zary <linux@...y.sk>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
CC:     Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Tim Waugh <tim@...erelk.net>, <linux-block@...r.kernel.org>,
        <linux-parport@...ts.infradead.org>, <linux-ide@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 11/32] parport_pc: add 16-bit and 8-bit fast EPP transfer
 flags

On 3/11/23 11:09 PM, Sergey Shtylyov wrote:

>> PARPORT_EPP_FAST flag currently uses 32-bit I/O port access for data
>> read/write (insl/outsl).
>> Add PARPORT_EPP_FAST_16 and PARPORT_EPP_FAST_8 that use insw/outsw
>> and insb/outsb (and PARPORT_EPP_FAST_32 as alias for PARPORT_EPP_FAST).
>>
>> Signed-off-by: Ondrej Zary <linux@...y.sk>
>> ---
>>  drivers/parport/parport_pc.c | 20 ++++++++++++++++----
>>  include/uapi/linux/parport.h |  3 +++
>>  2 files changed, 19 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c
>> index 5784dc20fb38..eda4e4e6d4e8 100644
>> --- a/drivers/parport/parport_pc.c
>> +++ b/drivers/parport/parport_pc.c
>> @@ -298,9 +298,15 @@ static size_t parport_pc_epp_read_data(struct parport *port, void *buf,
>>  		}
>>  		return got;
>>  	}
>> -	if ((flags & PARPORT_EPP_FAST) && (length > 1)) {
>> -		if (!(((long)buf | length) & 0x03))
>> +	if ((length > 1) && ((flags & PARPORT_EPP_FAST_32)
>> +			   || flags & PARPORT_EPP_FAST_16
>> +			   || flags & PARPORT_EPP_FAST_8)) {
> 
>    Why not:
> 
>> +		if ((flags & PARPORT_EPP_FAST_32)
>> +		    && !(((long)buf | length) & 0x03))
>>  			insl(EPPDATA(port), buf, (length >> 2));
>> +		else if ((flags & PARPORT_EPP_FAST_16)
>> +			 && !(((long)buf | length) & 0x01))
>> +			insw(EPPDATA(port), buf, length >> 1);
>>  		else
>>  			insb(EPPDATA(port), buf, length);
>

   Oopsie, s/th went wrong while editing... :-/

[...]

MBR, Sergey