Bug 75387

Summary:	DMA can't be set on (IDE) DVD players
Product:	[Retired] Red Hat Linux	Reporter:	rmhristev
Component:	kernel	Assignee:	Arjan van de Ven <arjanv>
Status:	CLOSED NOTABUG	QA Contact:	Brian Brock <bbrock>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	8.0
Target Milestone:	---
Target Release:	---
Hardware:	i386
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2002-10-07 22:46:40 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description rmhristev 2002-10-07 22:46:35 UTC

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.1) Gecko/20020830

Description of problem:
DMA cannot be set to "on" (with hdparm) on DVD players.
DMA capable CD-ROMs may also be affected.

Version-Release number of selected component (if applicable):


How reproducible:
Always

Steps to Reproduce:
1. assuming /dev/hdc as the DVD unit
2. hdparm -d1 /dev/hdc

	

Actual Results:  ~# hdparm -d1 /dev/hdc
/dev/hdc:
 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Operation not permitted
 using_dma    =  0 (off)

Expected Results:  ~# hdparm -d1 /dev/hdc
/dev/hdc:
 setting using_dma to 1 (on)
 using_dma    =  1 (on)


Additional info:

It used to work under RedHat 7.3

Workaround: upgrade the kernel to 2.4.19

Notes: DMA off leads to jerky playback and system responsivness

Comment 1 Arjan van de Ven 2002-10-08 08:21:36 UTC

From the release notes:

     o DMA is disabled on CD-ROM drives in this release in a different but
       more reliable way than previously. If you are sure that your CD-ROM
       drive is capable of IDE DMA, place the following line in the
       /etc/modules.conf file:

       options ide-cd dma=1