Sdram map

zxlwyx9219 · 04-26-2012, 12:59 AM

Hi :
I am a newby on linux driver developments. Nowadays I came cross a problem on the SDRAM mapping.
at the beginning of the system starting, i kept a reserved SDRAM for the jpeg driver as: s3c64xx: 4194304 bytes SDRAM reserved for jpeg at 0x5dbf8000;
at the jpeg driver, i used the ioremap founction to get the virtual address of the reserverd SDRAM(0x5dbf8000),but the ioremap says:
/*
* Don't allow RAM to be mapped - this causes problems with ARMv6+
*/
if (WARN_ON(pfn_valid(pfn)))
return NULL;
after ioremap i got the "NULL" pointer, so the jpeg driver failed. I didn't understand. So can anybody could show me how I could get the reserverd SDRAM for the jpeg driver?
I cat /proc/iomem, and it says:
50000000-5fffffff : System RAM
78800000-78bfffff : s3c-jpeg ........

Thanks very much!
lewis

zxlwyx9219 · 05-03-2012, 01:51 AM

Quote:

Originally Posted by zxlwyx9219

Hi :
I am a newby on linux driver developments. Nowadays I came cross a problem on the SDRAM mapping.
at the beginning of the system starting, i kept a reserved SDRAM for the jpeg driver as: s3c64xx: 4194304 bytes SDRAM reserved for jpeg at 0x5dbf8000;
at the jpeg driver, i used the ioremap founction to get the virtual address of the reserverd SDRAM(0x5dbf8000),but the ioremap says:
/*
* Don't allow RAM to be mapped - this causes problems with ARMv6+
*/
if (WARN_ON(pfn_valid(pfn)))
return NULL;
after ioremap i got the "NULL" pointer, so the jpeg driver failed. I didn't understand. So can anybody could show me how I could get the reserverd SDRAM for the jpeg driver?
I cat /proc/iomem, and it says:
50000000-5fffffff : System RAM
78800000-78bfffff : s3c-jpeg ........

Thanks very much!
lewis

I now found the questions, None replied but always thanks the same!