* Arm errata 752520
@ 2013-10-11 8:54 Matthieu CASTET
[not found] ` <20131011105401.443ccdc1-ITF29qwbsa/QT0dZR+AlfA@public.gmane.org>
0 siblings, 1 reply; 3+ messages in thread
From: Matthieu CASTET @ 2013-10-11 8:54 UTC (permalink / raw)
To: linux-arm-kernel
Hi,
tegra kernel on android tree have a workaround for cortex A9 errata
752520 :
"ARM: errata: 752520: Faulty arbitration between PLD and Cacheable TLB
requests may create a system deadlock."
https://android.googlesource.com/kernel/tegra/+/eabc12e1afe0bfc2f9e6f7bacae03985439df1a2%5E!/#F1
But this errata is not in mainline kernel. Do you know why ?
Should a patch be submitted to add it ?
Regards,
Matthieu
PS : There is also another patch for errata 720791.
^ permalink raw reply [flat|nested] 3+ messages in thread[parent not found: <20131011105401.443ccdc1-ITF29qwbsa/QT0dZR+AlfA@public.gmane.org>]
* Re: Arm errata 752520 2013-10-11 8:54 Arm errata 752520 Matthieu CASTET @ 2013-10-11 15:45 ` Stephen Warren 0 siblings, 0 replies; 3+ messages in thread From: Stephen Warren @ 2013-10-11 15:45 UTC (permalink / raw) To: Matthieu CASTET, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Cc: Will Deacon, Russell King, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On 10/11/2013 02:54 AM, Matthieu CASTET wrote: > Hi, > > tegra kernel on android tree have a workaround for cortex A9 errata > 752520 : You probably wanted to email the Tegra maintainers and list. > "ARM: errata: 752520: Faulty arbitration between PLD and Cacheable TLB > requests may create a system deadlock." > https://android.googlesource.com/kernel/tegra/+/eabc12e1afe0bfc2f9e6f7bacae03985439df1a2%5E!/#F1 > > But this errata is not in mainline kernel. Do you know why ? > Should a patch be submitted to add it ? Looking at that link, the WAR is enabled in the CPU's diagnostic register, and IIRC, writes to that register are only possible from secure mode. Since the Linux kernel does not always run in secure mode, and has no way of detecting whether it is, it cannot implement the WAR. Instead, the bootloader or secure firmware must do this before booting the kernel. > PS : There is also another patch for errata 720791. I assume there are similar limits on the "chicken power ctrl" register, whatever that is! (name take from the same kernel source tree you linked to above). ^ permalink raw reply [flat|nested] 3+ messages in thread
* Arm errata 752520 @ 2013-10-11 15:45 ` Stephen Warren 0 siblings, 0 replies; 3+ messages in thread From: Stephen Warren @ 2013-10-11 15:45 UTC (permalink / raw) To: linux-arm-kernel On 10/11/2013 02:54 AM, Matthieu CASTET wrote: > Hi, > > tegra kernel on android tree have a workaround for cortex A9 errata > 752520 : You probably wanted to email the Tegra maintainers and list. > "ARM: errata: 752520: Faulty arbitration between PLD and Cacheable TLB > requests may create a system deadlock." > https://android.googlesource.com/kernel/tegra/+/eabc12e1afe0bfc2f9e6f7bacae03985439df1a2%5E!/#F1 > > But this errata is not in mainline kernel. Do you know why ? > Should a patch be submitted to add it ? Looking at that link, the WAR is enabled in the CPU's diagnostic register, and IIRC, writes to that register are only possible from secure mode. Since the Linux kernel does not always run in secure mode, and has no way of detecting whether it is, it cannot implement the WAR. Instead, the bootloader or secure firmware must do this before booting the kernel. > PS : There is also another patch for errata 720791. I assume there are similar limits on the "chicken power ctrl" register, whatever that is! (name take from the same kernel source tree you linked to above). ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-10-11 15:45 UTC | newest]
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2013-10-11 8:54 Arm errata 752520 Matthieu CASTET
[not found] ` <20131011105401.443ccdc1-ITF29qwbsa/QT0dZR+AlfA@public.gmane.org>
2013-10-11 15:45 ` Stephen Warren
2013-10-11 15:45 ` Stephen Warren
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