From: Andrew Ruder andrew.ruder@elecsyscorp.com
Hey all,
Was tracking down an issue on a PXA270 based board where a long y-modem transfer would frequently deadlock the board in the middle of the transfer. Unfortunately I felt like I had opened pandora's box by looking around at other ports.
Very few ports were 32-bit rollover safe! Most looked like they would just skip a __udelay on roll-over. These are fixes for the couple I noticed that would potentially deadlock if __udelay crossed the 32-bit boundary. And some are so complicated that I didn't waste time looking at them.
get_ticks() which returns a unsigned long long had a variety of implementations. Some returned a number that wrapped at 32 bits which worked with some implementations of __udelay. Others returned a number that wraps at a fraction of 32-bits which would hit the roll-over issues at an unexpected place and fail even more often.
There is a lot of opportunity here for tons of code removal by moving more ports to the common code. Here are some notes that I took while going through some that might save someone some time. This was a very cursory look so my apologies if I have missed something.
** u-boot/arch/arm/cpu/arm1136/mx31/timer.c:98:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay() depends on 64-bit value - HANGS ** u-boot/arch/arm/cpu/arm1136/mx35/timer.c:75:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay() depends on 64-bit value - HANGS ** u-boot/arch/arm/cpu/arm1176/bcm2835/timer.c:37:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay() is safe ** u-boot/arch/arm/cpu/arm1176/tnetv107x/timer.c:67:20:unsigned long long get_ticks(void) get_ticks() isn't even a 32-bit number __udelay() is safe ** u-boot/arch/arm/cpu/arm920t/a320/timer.c:74:20:unsigned long long get_ticks(void) get_ticks() returns 64-bit number __udelay() is safe ** u-boot/arch/arm/cpu/arm920t/at91/timer.c:115:20:unsigned long long get_ticks(void) get_ticks() isn't even a 32-bit number __udelay() is safe ** u-boot/arch/arm/cpu/arm920t/ep93xx/timer.c:58:20:unsigned long long get_ticks(void) get_ticks() returns 64-bit number __udelay() is safe until 64-bit rollover ** u-boot/arch/arm/cpu/arm920t/imx/timer.c:70:20:unsigned long long get_ticks(void) get_ticks() returns a 32-bit number __udelay is safe ** u-boot/arch/arm/cpu/arm920t/s3c24x0/timer.c:110:20:unsigned long long get_ticks(void) get_ticks() is complicated. tbu abused for something else __udelay might be safe? It handles 32-bit rollover correctly if get_ticks() is really a 32-bit number ** u-boot/arch/arm/cpu/arm926ejs/armada100/timer.c:182:20:unsigned long long get_ticks(void) get_ticks() isn't a 32-bit number __udelay completely doesn't handle roll-over ** u-boot/arch/arm/cpu/arm926ejs/at91/timer.c:75:20:unsigned long long get_ticks(void) get_ticks() returns 64-bit number __udelay handles roll-over looks perfect ** u-boot/arch/arm/cpu/arm926ejs/davinci/timer.c:56:20:unsigned long long get_ticks(void) get_ticks() returns 64-bit number chooses to ignore roll-over ** u-boot/arch/arm/cpu/arm926ejs/kirkwood/timer.c:145:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number no idea, too complicated ** u-boot/arch/arm/cpu/arm926ejs/mb86r0x/timer.c:65:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay doesn't handle roll-over ** u-boot/arch/arm/cpu/arm926ejs/lpc32xx/timer.c:74:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay is safe (doesn't handle roll-over - doesn't need to) ** u-boot/arch/arm/cpu/arm926ejs/mx27/timer.c:111:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay broken ** u-boot/arch/arm/cpu/arm926ejs/mxs/timer.c:81:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay complicated ** u-boot/arch/arm/cpu/arm926ejs/nomadik/timer.c:63:20:unsigned long long get_ticks(void) get_ticks() isn't a 32-bit number __udelay complicated ** u-boot/arch/arm/cpu/arm926ejs/omap/timer.c:140:20:unsigned long long get_ticks(void) get_ticks() isn't a 32-bit number __udelay looks good ** u-boot/arch/arm/cpu/arm926ejs/orion5x/timer.c:159:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay complicated ** u-boot/arch/arm/cpu/arm926ejs/pantheon/timer.c:189:20:unsigned long long get_ticks(void) get_ticks() doesn't return a 32-bit number __udelay doesn't handle roll-over ** u-boot/arch/arm/cpu/arm926ejs/spear/timer.c:111:20:unsigned long long get_ticks(void) get_ticks() doesn't return a 32-bit number __udelay looks good ** u-boot/arch/arm/cpu/armv7/arch_timer.c:24:20:unsigned long long get_ticks(void) get_ticks() returns 64-bit number __udelay doesn't handle 64-bit roll-over ** u-boot/arch/arm/cpu/armv7/at91/timer.c:78:20:unsigned long long get_ticks(void) get_ticks() returns 64-bit number __udelay looks good looks perfect ** u-boot/arch/arm/cpu/armv7/omap-common/timer.c:96:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay complicated but looks good ** u-boot/arch/arm/cpu/armv7/rmobile/timer.c:77:20:unsigned long long get_ticks(void) get_ticks() returns a 64-bit number __udelay looks good ** u-boot/arch/arm/cpu/armv7/s5p-common/timer.c:120:20:unsigned long long get_ticks(void) get_ticks() doesn't return a 32-bit number __udelay looks good ** u-boot/arch/arm/cpu/armv7/sunxi/timer.c:101:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay off by 1 on roll-over ** u-boot/arch/arm/cpu/armv7/vf610/timer.c:49:20:unsigned long long get_ticks(void) get_ticks() returns 64-bit number __udelay looks good ** u-boot/arch/arm/cpu/armv7/u8500/timer.c:123:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay off by 1 on rollover ** u-boot/arch/arm/cpu/armv7/zynq/timer.c:154:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay complicated ** u-boot/arch/arm/cpu/pxa/timer.c:45:20:unsigned long long get_ticks(void) get_ticks() returns a 32-bit number __udelay depends on 64-bit - HANGS ** u-boot/arch/arm/cpu/sa1100/timer.c:58:20:unsigned long long get_ticks(void) get_ticks() returns a 32-bit number __udelay looks good ** u-boot/arch/arm/imx-common/timer.c:74:20:unsigned long long get_ticks(void) get_ticks() returns 64-bit number __udelay doesn't handle 64-bit roll-over ** u-boot/arch/avr32/cpu/interrupts.c:36:20:unsigned long long get_ticks(void) get_ticks() returns 64-bit number __udelay() correctly handles overflow ** u-boot/arch/blackfin/cpu/interrupts.c:39:20:unsigned long long get_ticks(void) get_ticks() returns a 32-bit number __udelay() looks ok i think (pretty complicated) ** u-boot/arch/m68k/lib/time.c:179:20:unsigned long long get_ticks(void) get_ticks() returns a 32-bit number __udelay() looks ok ** u-boot/arch/microblaze/cpu/timer.c:80:20:unsigned long long get_ticks(void) get_ticks() returns a 32-bit number __udelay() looks ok. ** u-boot/arch/mips/cpu/mips32/time.c:58:20:unsigned long long get_ticks(void) get_ticks() returns a 32-bit number __udelay() complicated ** u-boot/arch/mips/cpu/mips64/time.c:58:20:unsigned long long get_ticks(void) get_ticks() might return 64-bit __udelay() complicated ** u-boot/arch/nds32/cpu/n1213/ag101/timer.c:173:20:unsigned long long get_ticks(void) get_ticks() returns 32-bit number __udelay() off-by-1 on roll-over ** u-boot/arch/nds32/cpu/n1213/ag102/timer.c:173:20:unsigned long long get_ticks(void) see above - same code
Andrew Ruder (3): arm: pxa: use common timer functions arm: mx31: use common timer functions arm: mx35: use common timer functions
arch/arm/cpu/arm1136/mx31/timer.c | 104 +----------------------------- arch/arm/cpu/arm1136/mx35/timer.c | 83 ------------------------ arch/arm/cpu/pxa/timer.c | 69 +------------------- arch/arm/include/asm/arch-mx31/imx-regs.h | 10 +++ arch/arm/include/asm/arch-mx35/imx-regs.h | 12 ++++ include/configs/pxa-common.h | 13 ++++ 6 files changed, 38 insertions(+), 253 deletions(-)
Cc: Marek Vasut marex@denx.de