From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Kuzminsky Subject: Re: what is hdparm doing? Date: Tue, 28 Feb 2006 20:22:21 -0700 Message-ID: References: <4404F89C.8040008@rtr.ca> Return-path: Received: from rwcrmhc14.comcast.net ([216.148.227.154]:14288 "EHLO rwcrmhc14.comcast.net") by vger.kernel.org with ESMTP id S932522AbWCADUW (ORCPT ); Tue, 28 Feb 2006 22:20:22 -0500 Received: from seb (helo=highlab.com) by highlab.com with local-esmtp (Exim 4.50) id 1FEHuv-0004mb-VL for linux-ide@vger.kernel.org; Tue, 28 Feb 2006 20:22:21 -0700 In-reply-to: <4404F89C.8040008@rtr.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: linux-ide@vger.kernel.org Mark Lord wrote: > Sebastian Kuzminsky wrote: > > Hi folks, hdparm's got me confused. > .. > > "hdparm /dev/hda" says: > . > > DMA: mdma0 mdma1 *mdma2 > > Cycle time: min=120ns recommended=120ns > > PIO: pio0 pio1 pio2 pio3 pio4 > > Cycle time: no flow control=120ns IORDY flow control=120ns > .. > > The *mdma2 means, that if you were to issue a READ_DMA (or WRITE_DMA) > command to the drive, the drive is expecting the host to use > the multiword-dma-2 protocol and timings for it. > > Meanwhile, the host may, at its option, simply use PIO commands (READ, WRITE) > instead of DMA, any time it chooses. > > Drives have both a DMA mode, and a PIO mode, each of which is selected > and used independently of the other. Ok thanks! So how do I know what PIO mode the drive wants to use? And how do I tell the HBA what PIO mode to use? -- Sebastian Kuzminsky