From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753792AbZCDPn0 (ORCPT ); Wed, 4 Mar 2009 10:43:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752090AbZCDPnR (ORCPT ); Wed, 4 Mar 2009 10:43:17 -0500 Received: from ns2.mvista.com ([63.81.120.155]:31279 "EHLO imap.sh.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751448AbZCDPnQ (ORCPT ); Wed, 4 Mar 2009 10:43:16 -0500 Message-ID: <49AEA1B1.3050008@ru.mvista.com> Date: Wed, 04 Mar 2009 18:43:45 +0300 From: Sergei Shtylyov Organization: MontaVista Software Inc. User-Agent: Mozilla/5.0 (X11; U; Linux i686; rv:1.7.2) Gecko/20040803 X-Accept-Language: ru, en-us, en-gb MIME-Version: 1.0 To: Sergei Shtylyov Cc: Bartlomiej Zolnierkiewicz , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 13/18] ide: use ->tf_load in SELECT_DRIVE() References: <20080620213323.13202.71450.sendpatchset@localhost.localdomain> <200902162251.49271.bzolnier@gmail.com> <499A0D0B.7070007@ru.mvista.com> <200902171543.21892.bzolnier@gmail.com> <499AD872.2060605@ru.mvista.com> In-Reply-To: <499AD872.2060605@ru.mvista.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, I wrote: >>>>>>>> There should be no functional changes caused by this patch. >>>>>>>> Signed-off-by: Bartlomiej Zolnierkiewicz >>>>>>>> Index: b/drivers/ide/ide-iops.c >>>>>>>> =================================================================== >>>>>>>> --- a/drivers/ide/ide-iops.c >>>>>>>> +++ b/drivers/ide/ide-iops.c >>>>>>>> @@ -88,11 +88,15 @@ void SELECT_DRIVE (ide_drive_t *drive) >>>>>>>> { >>>>>>>> ide_hwif_t *hwif = drive->hwif; >>>>>>>> const struct ide_port_ops *port_ops = hwif->port_ops; >>>>>>>> + ide_task_t task; >>>>>>>> if (port_ops && port_ops->selectproc) >>>>>>>> port_ops->selectproc(drive); >>>>>>>> >>>>>>>> - hwif->OUTB(drive->select.all, hwif->io_ports.device_addr); >>>>>>>> + memset(&task, 0, sizeof(task)); >>>>>>>> + task.tf_flags = IDE_TFLAG_OUT_DEVICE; >>>>>>>> + >>>>>>>> + drive->hwif->tf_load(drive, &task); >>>>>>> This actually doesn't seem like a bright idea to me, >>>>>>> considering that this gets called when starting every request. >>>>>>> How will you look at me adding the transport method for writing >>>>>>> this register? :-) >>>> Please check profiles first -- it might not be worth it. [1] >>>>>> Convert SELECT_DRIVE() to use ->tf_load instead of ->OUTB. >>>>>> OTOH, adding such a "backdoor" to the taskfile doesn't seem very >>>>>> consistent... well, I'm not excited about the whole idea >>>>>> conversion to tf_{load|read}() -- it's not clear what exactly this >>>>>> bought us. >>>> This was explained some months ago already, so just to recall -- it was >>>> a part of a bigger work removing duplicated code and allowing >>>> abstraction >>>> of the ATA logic. >>>> Anyway this is not set in a stone so if you have proposal of a better >>>> approach please come forward with it. >>> Er... I think that the previous IN()/OUT() methods were better. >>> Note that we ended up using the local version of them in the dafault >>> ide_tf_{load}read}() anyway -- as Alan has pointed out it might be worth >> During ide_tf_{load,read}() addition I was a bit too optimistic about >> the possibility of the quick io{read,write}* conversion later... >>> splitting those into I/O and memory space versions... although given >>> general slowness of the I/O accesses, this is probably not going to >>> win much speed-wise. >> Maybe it would be worth to add ->tf_{inb,outb} to struct ide_tp_ops >> and convert default tp_ops to use them... OTOH we should reinvestigate >> the io{read,write}*() way first (maybe things have improved there)... > Yes, let's not be hasty here... What I certainly don't like is how tf_load/read() handle LBA48: there's much of the code duplication going on. I'll think what can be done about it but it may not be easy to tackle... it looks like 'struct ide_taskfile' needs to be reorganized to include 2 6-byte sub-structures. >> Thanks, >> Bart MBR, Sergei