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Old 04-26-2012, 12:59 AM   #1
zxlwyx9219
LQ Newbie
 
Registered: Jun 2011
Posts: 16

Rep: Reputation: Disabled
Question Sdram map


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
 
Old 05-03-2012, 01:51 AM   #2
zxlwyx9219
LQ Newbie
 
Registered: Jun 2011
Posts: 16

Original Poster
Rep: Reputation: Disabled
Quote:
Originally Posted by zxlwyx9219 View Post
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!
 
  


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