From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH] remove ide-scsi Date: Sun, 07 Dec 2008 02:19:03 +0300 Message-ID: <493B0867.5020700@ru.mvista.com> References: <20081203103856S.fujita.tomonori@lab.ntt.co.jp> <200812061551.08525.bzolnier@gmail.com> <20081206120001.3580b9e3@tuna> <200812062241.35601.bzolnier@gmail.com> <20081206222423.04aada70@lxorguk.ukuu.org.uk> <493B022B.3050406@ru.mvista.com> <20081206230227.07b00e2f@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from homer.mvista.com ([63.81.120.155]:8755 "EHLO imap.sh.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753279AbYLFXTN (ORCPT ); Sat, 6 Dec 2008 18:19:13 -0500 In-Reply-To: <20081206230227.07b00e2f@lxorguk.ukuu.org.uk> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alan Cox Cc: Bartlomiej Zolnierkiewicz , =?ISO-8859-1?Q?Dan_?= =?ISO-8859-1?Q?No=E9?= , James Bottomley , Christoph Hellwig , FUJITA Tomonori , linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, osst@riede.org Hello. Alan Cox wrote: >> Oh, yes. SCSI emulation is just what Linux embedded world is asking >> for... >> > > Well ATAPI is SCSI emulation (its a sort of pidgin SCSI admittedly). > ATAPI is SCSI transport (with maybe some quirks at SCSI command level tho, IIRC). ATA is neither thansport nor does it map to SCSI 1:1. The code for emulating SCSI on ATA only burdens the kernel (and causes user complaints about changing disk names from /dev/hdx to /dev/sda :-). > I'm actually seeing two strands of requests (including from embedded) > > - CF only small "dumb as president" type driver that is written to be as > compact as possible and preferably considers IRQs as optional > Yes, support for IRQ-less CF is what IDE core lacks. I must note however that IRQ-less mode looks inherently risky to me because of the raciness of tbothe the ATA spec and its implimentatin WRT the "interrupt pending" state. I may be mistaking but someone of T13 experts (Hale Landis I guess) told me that the devices require that state to be cleared to proceed with the command, and that's what the fast polling host is likely to fail at because it doesn't know if rthe device has actually entered this state when BSY is cleared... Oh well, that's an old story... > - Full SATA and NCQ aware platform support. > I don't see how SATA/NCQ support is connected to SCSI. > although the former is growing quieter and it seems the CF formfactor is > We're seeing the IRQ-less CF driver submitted for the Octeon SoC (which employs up to 16 MIPS cores) -- though it's probably needed only for the development boards... :-) > just too clunky for embedded nowdays, especially with the horrendously > complex and pricy connector - and is being eliminated by MMC/SD and > friends. > Oh, don't tell me about that MMC crap. :-) For some reason they keep wring the card insert and write protect signals via GPIO, not directly into controller (and it's yet good if directly into SoC's own GPIO, not an expander) -- which requires the drivers to call the platform code hooks. :-( > Alan > MBR, Sergei