On Wed, Jan 09, 2008 at 10:16:01PM +0800, Lonsn wrote: > Hi: > I'm now using s3cmci > patch(http://svnweb.openmoko.org/branches/src/target/kernel/2.6.21.x/patches/s3c_mci.patch?rev=2805&view=auto) > and it works well. The SD card write speed is about 26Mbits/s(S3C2440A > 400MHz, Sandisk UltraIII 2GB sd card). > But the CPU load is too heavy(80%). So I want to let s3cmci driver work in > DMA mode. I changed host->dodma = 1;
> But it doesn't work and the driver cann't detect the sd card. Does > anyone use the s3cmci driver in DMA mode successfully? I don't think anyone has used it with DMA in a long time (probably no later than 2.6.14 or even 2.6.10). There have been DMA API changes that might not be reflected in the driver. I strongly recommend you use the driver that is present in the 2.6.24.x branch of the openmoko svn (which is also what has been submitted to linux-arm-kernel some weeks back). > Another question: Can sd card work speed be more than 25MHz? As I > know, the maximum sdi clock of S3C2440A is 33MHz(APB clock=67MHz, > prescaler value=1) and UltraIII sd card can support 40MHz > frequency(20MBytes/s). If we can let s3cmci driver works in 33MHz > modes, maybe the sd card IO performance could be increased a lot. But > the sdi clock works only 22.5MHz(prescaler value=2) mode now. I don't think anyone has tried this yet. -- - Harald Welte <[EMAIL PROTECTED]> http://openmoko.org/ ============================================================================ Software for the world's first truly open Free Software mobile phone
