From mboxrd@z Thu Jan 1 00:00:00 1970 From: vitja.makarov@gmail.com (Vitja Makarov) Date: Thu, 11 Nov 2010 15:50:12 +0300 Subject: [AT91SAM9260] kernel hang in at91sam926x_pit_reset() In-Reply-To: <201011111345.42080.alexander.stein@systec-electronic.com> References: <201011111345.42080.alexander.stein@systec-electronic.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 2010/11/11 Alexander Stein : > On Thursday 11 November 2010, 12:41:48 Vitja Makarov wrote: >> Hi! >> >> I've recently found that our new AT91SAM9260 boards does not work with >> linux out of the box. >> The only thing changed is CPU revision now it is "Rev. B' (old boards >> used "Rev. A" CPUs) >> >> >> So after uncompressing kernel it writes. "Booting kernel..." that's >> all. Kernel hangs. >> >> I found that it hangs in ?at91sam926x_time.c:at91sam926x_pit_reset(): >> >> Bit in AT91_PIT_PIVR register never clears... so I add timeout for >> this loop and kernel boots as expected. >> >> static void at91sam926x_pit_reset(void) >> { >> <------>/* Disable timer and irqs */ >> <------>at91_sys_write(AT91_PIT_MR, 0); >> >> <------>/* Clear any pending interrupts, wait for PIT to stop counting */ >> <------>while (PIT_CPIV(at91_sys_read(AT91_PIT_PIVR)) != 0) >> <------><------>cpu_relax(); >> >> <------>/* Start PIT but don't enable IRQ */ >> <------>at91_sys_write(AT91_PIT_MR, (pit_cycle - 1) | AT91_PIT_PITEN); >> } > > This won't work as you cannot set PIT_PITEN until the PIT has stopped > (UserManuel 17.3), read as CPIV is 0. You should check if and why CPIV isn't > increasing. > > Best regards > Alexander > Could it be hardware bug? With revision A it works. Do you have success on use rev B. CPUs? May be the problem is in u-boot or initial loader?