Messages in this thread | | | Subject | Re: [PATCH -next] irq-chip/gic-v3-its: Fixed an issue where the ITS executes the residual commands in the queue again when the ITS wakes up from sleep mode. | From | "xuqiang (M)" <> | Date | Fri, 6 Nov 2020 18:05:36 +0800 |
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在 2020/11/5 22:24, Marc Zyngier 写道: > On 2020-11-05 14:06, xuqiang (M) wrote: >> 在 2020/11/5 21:12, Marc Zyngier 写道: >>> Please don't top-post. >>> >>> On 2020-11-05 11:54, xuqiang (M) wrote: >>>> The kernel sends three commands in the following sequence: >>>> >>>> 1.mapd(deviceA, ITT_addr1, valid:1) >>>> >>>> 2.mapti(deviceA):ITS write ITT_addr1 memory; >>>> >>>> 3.mapd(deviceA, ITT_addr1, valid:0) and kfree(ITT_addr1); >>>> >>>> 4.mapd(deviceA, ITT_addr2, valid:1); >>>> >>>> 5.mapti(deviceA):ITS write ITT_addr2 memory; >>>> >>>> In this case, the processor enters the sleep mode. After the kernel >>>> performs the suspend operation, the firmware performs the store >>>> operation and saves GITS_CBASER and GITS_CWRITER registers. >>>> >>>> Then, the processor is woken up, and the firmware restores GITS_CBASER >>>> and GITS_CWRITER registers. Because GITS_CWRITER register is not 0, >>>> ITS will read the above command sequence execution from the command >>>> queue, causing ITT_addr1 memory to be trampled. >>> >>> This cannot work. By doing a memset on the command queue, you are >>> only feeding crap to the ITS (command 0 simply does not exist). >>> Consider yourself lucky that it doesn't just lock-up. >>> >>> What needs to happen is the restore sequence that is already in the >>> driver, so that the command queue is in a sane state before re-enabling >>> the ITS. >>> >>> M. >> >> >> On my platform, ITS_FLAGS_SAVE_SUSPEND_STATE is not set, thus >> the first if condition in its_save_disable under list_for_each_entry >> goes >> to the continue, however, I want to set the GITS_CWRITER to 0 at the >> end of list_for_each_entry. >> >> Do you have any suggestions about how to do this? > > That's pretty much dropping the checks for ITS_FLAGS_SAVE_SUSPEND_STATE, > isn't it? But I assume your ITS is already enabled by the time you > reenter > the kernel? If so, I bet your firmware is doing more than just writing > to CBASER and CWRITER... > > M.
Yes, you are right.My firmware stores GITS_CTRL,GITS_CBASER,GITS_CWRITER
and GITS_BASER<n> in the suspend, and restores these registers in the resume.
So I will drop the checks for ITS_FLAGS_SAVE_SUSPEND_STATE. In the case of ITS disabled,
set the GITS_CWRITER to 0.
Thanks
Xu.
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