From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: what is hdparm doing? Date: Tue, 28 Feb 2006 20:27:56 -0500 Message-ID: <4404F89C.8040008@rtr.ca> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from rtr.ca ([64.26.128.89]:8686 "EHLO mail.rtr.ca") by vger.kernel.org with ESMTP id S932641AbWCAB2C (ORCPT ); Tue, 28 Feb 2006 20:28:02 -0500 In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Sebastian Kuzminsky Cc: linux-ide@vger.kernel.org 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. Cheers