From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bartlomiej Zolnierkiewicz Subject: Re: [PATCH] pata_it8213: MWDMA0 is unsupported Date: Thu, 26 Nov 2009 19:27:00 +0100 Message-ID: <200911261927.00597.bzolnier@gmail.com> References: <200911261728.36433.bzolnier@gmail.com> <200911261903.01199.bzolnier@gmail.com> <4B0EC52B.2070805@ru.mvista.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ew0-f219.google.com ([209.85.219.219]:59798 "EHLO mail-ew0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750872AbZKZS2C (ORCPT ); Thu, 26 Nov 2009 13:28:02 -0500 In-Reply-To: <4B0EC52B.2070805@ru.mvista.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Sergei Shtylyov Cc: Alan Cox , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org On Thursday 26 November 2009 07:12:59 pm Sergei Shtylyov wrote: > Bartlomiej Zolnierkiewicz wrote: > > >>>>>MWDMA0 timings cannot be met with the PIIX based controller > >>>>>programming interface. > >>> > >>>>>This change should be safe as this is how we have been doing > >>>>>things in IDE it8213 host driver for years. > >>> > >>>>>Signed-off-by: Bartlomiej Zolnierkiewicz > >>>>>--- > >>>>>Verified with the documentation (similar case as with pata_efar). > > >>>>Uhhh, no... > > >>>>Too many damn drivers. > > >>>>Too much damn duplication. > > >>>>Too much damn subtle differences here and there. > > >>>>The hardware is probably fine for MWMDA0 when it comes to pata_{efar,it8213}, > >>>>it just not documented properly in the data sheet. > > >>> How so with pata_efar? The active/recovery bitfields are still 2-bit > >>>wide, no? > > >>Yes but when TIMEx bit is disabled we are using XFER_PIO_SLOW timings. > > 600 ns cycle vs spec'ed 480 ns? Is it really worth it? 960 ns actually > >>All data sheets including original Intel ones are a complete crap when it > >>comes to explicitly documenting this behavior. > > > OTOH all drivers set TIMEx for MWDMA0 currently.. ? > > ... which would give a grossly overclocked timing. Except ata_piix which blacklists MWDMA0 for _all_ PATA controllers.. :) I'm leaving my patches as they were for now, unless somebody wants to untangle this mess this is a safest and quickest way forward.. -- Bartlomiej Zolnierkiewicz