On Fri, Jan 18, 2013 at 12:59:48PM +0000, Yi Qingliang wrote: > Thanks! > > So tired... But, maybe you should congratulate me:). > I got the root cause finally, although I still have doubt.
Please submit your patch to the kernels people. Simply to make the tty code more reliable :) > 1. same binary (barebox+kernel+rootfs) running well on mini2440 > > 2. I compared the serial related registers in CPU, and found only one > different: > the register "UCON0"'s bitfield [11:10], ie. clock selection. > on mini2440, it is 10, on my s3c2442, it is 00. > on mini2440, the tty's wait_until_sent will return quickly, not on s3c2442. > > on mini2440, the first try in waiting will found there is something not > sended, > the second try will found it cleared. > > but on s3c2442, NOT so. > > > 3. check the tty driver, I found in samsung.c, there is one function is > related with that: > 's3c24xx_serial_setsource' > > 4. and then found the caller: 's3c24xx_serial_set_termios'. I have added > printk in it. and the different it is. > > 5. in 's3c24xx_serial_set_termios', it will find clock in system info, > on mini2440, it found, on my s3c2442, no luck. > > 6. add printk to print out all clocks. > on my s3c2442, there is not 'clk_uart_baud[1-3]' > > 7, I continue search the clock sources, found that in arch/arm/mach- > s3c24xx/clock-s3c2442.c. but it is only registered for s3c2440, not s3c2442. > > 8. I checked directory mach-s3c24xx, found file 's3c2442.c' had registered > some > clock info for s3c2442, but only camera related. > > 9. I added register routine in clock-s3c2440.c to register for s3c2442, > accroding to registering for s3c2440. (dropped camera related because > s3c2442.c registered that already, but different with s3c2440's) > > 10. DONE!!!!! the problem freezing 30section missed. then the getty will give > login prompt without '-i' option. > > 11. maybe it is done! but I don't know why kernel code have not register uart > related clock info for s3c2442, and I don't know where I can get the answer. > > > > On Thursday, January 17, 2013 08:52:03 AM Dr. Werner Fink wrote: > > On Thu, Jan 17, 2013 at 08:42:51AM +0000, Yi Qingliang wrote: > > > On Wednesday, January 16, 2013 08:56:17 AM Dr. Werner Fink wrote: > > > > On Wed, Jan 16, 2013 at 10:08:50AM +0000, niqingliang2...@gmail.com > wrote: > > > > > On Wednesday, January 16, 2013 09:44:10 AM niqingliang2...@gmail.com > > > > > > wrote: > > > > > > On Tuesday, January 15, 2013 04:56:44 PM Dr. Werner Fink wrote: > > > > > > > On Tue, Jan 15, 2013 at 11:11:21PM +0800, Yi Qingliang wrote: > > > > > > > > On Tuesday, January 15, 2013 12:16:46 PM Dr. Werner Fink wrote: > > > > > > > > > On Tue, Jan 15, 2013 at 06:42:26PM +0000, > > > > > > > > > niqingliang2...@gmail.com > > > > > > > > > > why the close(fd) freeze for 30seconds? > > > > > is it related with serial setting? or serial driver? > > > > > > > > That more kernel driver related. Sorry, but I'm not familiar with this > > > > kind > > > > of serial device nor driver :( > > > > > > which tty the sysvinit will open if the kernel parameter is > > > 'console=ttySAC0"? I debugged the sysvinit, it open the /dev/console, is > > > that normal? > > Yes as /dev/console is the system console and the real devices used for > > the console are handled by the kernel. Compare with e.g. > > > > cat /proc/consoles > > > > which will list all devices used for the system console[1]. Even printers > > could be used for a channel of the system console. > > > > > > Werner > > > > [1] https://patchwork.kernel.org/patch/461091/ > -- > Nanjing Jilong > Yi Qingliang > niqingliang2...@gmail.com Werner -- "Having a smoking section in a restaurant is like having a peeing section in a swimming pool." -- Edward Burr
