[Alsa-devel] runtime-dma_addr
hi, Can someone please explain me what is the difference between runtime-dma_addr and runtime-dma_area where runtime = substream-runtime I am getting a very strange problem where I am getting a rumtime-dma_addr value as 0 while runtime-dma_area is a proper value. Any hints will be helpful warm regards -kshitij --- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356alloc_id=3438op=click ___ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
Re: [Alsa-devel] runtime-dma_addr
On Wed, 3 Mar 2004, Gupta, Kshitij wrote: hi, Can someone please explain me what is the difference between runtime-dma_addr and runtime-dma_area where runtime = substream-runtime I am getting a very strange problem where I am getting a rumtime-dma_addr value as 0 while runtime-dma_area is a proper value. Any hints will be helpful dma_area is virtual address (visible from the CPU view) dma_addr is the physical bus address (visible from the hardware) Jaroslav - Jaroslav Kysela [EMAIL PROTECTED] Linux Kernel Sound Maintainer ALSA Project, SuSE Labs --- SF.Net is sponsored by: Speed Start Your Linux Apps Now. Build and deploy apps Web services for Linux with a free DVD software kit from IBM. Click Now! http://ads.osdn.com/?ad_id=1356alloc_id=3438op=click ___ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
Re: [Alsa-devel] runtime-dma_addr
At Wed, 3 Mar 2004 23:47:10 +0530, Gupta, Kshitij wrote: hi, Can someone please explain me what is the difference between runtime-dma_addr and runtime-dma_area where runtime = substream-runtime dma_addr is the physical address of the buffer. this is valid for PCI, ISA and SBUS buffers. dma_area is the virtual address of the buffer. I am getting a very strange problem where I am getting a rumtime-dma_addr value as 0 while runtime-dma_area is a proper value. if you use the buffer of SNDRV_DMA_TYPE_CONTINUOUS, dma_addr is not set, because the virtual pointer cannot be resolved to the physical address uniquely. Takashi --- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470alloc_id=3638op=click ___ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
Re: [Alsa-devel] runtime-dma_addr
On Wed, Mar 03, 2004 at 07:29:19PM +0100, Jaroslav Kysela wrote: On Wed, 3 Mar 2004, Gupta, Kshitij wrote: hi, Can someone please explain me what is the difference between runtime-dma_addr and runtime-dma_area where runtime = substream-runtime I am getting a very strange problem where I am getting a rumtime-dma_addr value as 0 while runtime-dma_area is a proper value. Any hints will be helpful dma_area is virtual address (visible from the CPU view) dma_addr is the physical bus address (visible from the hardware) Not quite true - dma_addr is the bus address. Linux has three memory spaces: virtual, physical and bus. The value returned from dma_alloc_coherent/pci_alloc_consistent has always been this magical bus address which may be unique to the device it's being programmed into. This is why DMA-mapping.txt says: pci_alloc_consistent returns two values: the virtual address which you can use to access it from the CPU and dma_handle which you pass to the card. rather than calling dma_handle the physical address. -- Russell King Linux kernel2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ 2.6 Serial core --- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470alloc_id=3638op=click ___ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
