|To:||Shmulik Ladkani <firstname.lastname@example.org>|
|Subject:||Re: serial port 8250 messed up after coverting from little endian to big endian on kernel 2.6.31|
|From:||Sergei Shtylyov <email@example.com>|
|Date:||Wed, 28 Oct 2009 14:04:00 +0300|
|Cc:||firstname.lastname@example.org, Florian Fainelli <email@example.com>, firstname.lastname@example.org, linux-mips <email@example.com>, firstname.lastname@example.org|
|References:||<email@example.com> <4AD906D8.firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org>|
|User-agent:||Thunderbird 18.104.22.168 (Windows/20090812)|
Hello. Shmulik Ladkani wrote:
Thanks, Florian. I found the cause of the problem. My board is 32 bit based, so each serial port register is 32bit even only 8 bit is used. So when the board is switched endianess, I need to change the address offset to access the same registers. For example, original RHR register address is 0x8001000 with little endian mode. With big endian, I need to access it as 0x8001003.I assume your uart_port's iotype is defined as UPIO_MEM32.
He wouldn't have to add 3 to the register addresses then.
UPIO_MEM32 makes 8250 access serial registers using readl/writel (which might be a problem for big-endian), while UPIO_MEM makes 8250 access the registers using readb/writeb.
Both may be a problem for big endian.
Maybe you should try UPIO_MEM (assuming hardware allows byte access).
Contrarywise, I think he now has UPIO_MEM and needs to try UPIO_MEM32. WBR, Sergei
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