acpi_target_system_state() seems to be almost the thing we're looking for, except that it's only valid in the suspend callbacks since it gets reset to ACPI_STATE_S0 when resuming. So probably we want something else ... -Daniel On Wed, Sep 23, 2015 at 6:28 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > Actually add Rafael this time around ... > -Daniel > > On Wed, Sep 23, 2015 at 6:27 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: >> On Wed, Sep 23, 2015 at 9:57 AM, Daniel Vetter <daniel@xxxxxxxx> wrote: >>> On Thu, Sep 17, 2015 at 12:53:21AM +0530, Animesh Manna wrote: >>>> >>>> >>>> On 9/14/2015 1:16 PM, Daniel Vetter wrote: >>>> >On Fri, Sep 11, 2015 at 12:36:24AM +0530, Animesh Manna wrote: >>>> >> >>>> >>On 9/10/2015 8:15 PM, Daniel Vetter wrote: >>>> >>>On Thu, Sep 10, 2015 at 01:58:54AM +0530, Animesh Manna wrote: >>>> >>>>On 9/2/2015 2:24 PM, Daniel Vetter wrote: >>>> >>>>>On Wed, Aug 26, 2015 at 07:40:54PM +0530, Animesh Manna wrote: >>>> >>>>>>On 8/26/2015 6:40 PM, Daniel Vetter wrote: >>>> >>>>>>>On Wed, Aug 26, 2015 at 01:36:05AM +0530, Animesh Manna wrote: >>>> >>>>>>>>Dmc will restore the csr program except DC9, cold boot, >>>> >>>>>>>>warm reset, PCI function level reset, and hibernate/suspend. >>>> >>>>>>>> >>>> >>>>>>>>intel_csr_load_program() function is used to load the firmware >>>> >>>>>>>>data from kernel memory to csr address space. >>>> >>>>>>>> >>>> >>>>>>>>All values of csr address space will be zero if it got reset and >>>> >>>>>>>>the first byte of csr program is always a non-zero if firmware >>>> >>>>>>>>is loaded successfuly. Based on hardware status will load the >>>> >>>>>>>>firmware. >>>> >>>>>>>> >>>> >>>>>>>>Without this condition check if we overwrite the firmware data the >>>> >>>>>>>>counters exposed for dc5/dc6 (help for debugging) will be nullified. >>>> >>>>>>Bacause of the above reason mentioned just above we need to block firmware loading again. >>>> >>>>>>So only WARN_ON will not help. >>>> >>>>>> >>>> >>>>>> >>>> >>>>>>>>v1: Initial version. >>>> >>>>>>>> >>>> >>>>>>>>v2: Based on review comments from Daniel, >>>> >>>>>>>>- Added a check to know hardware status and load the firmware if not loaded. >>>> >>>>>>>> >>>> >>>>>>>>Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx> >>>> >>>>>>>>Cc: Damien Lespiau <damien.lespiau@xxxxxxxxx> >>>> >>>>>>>>Cc: Imre Deak <imre.deak@xxxxxxxxx> >>>> >>>>>>>>Cc: Sunil Kamath <sunil.kamath@xxxxxxxxx> >>>> >>>>>>>>Signed-off-by: Animesh Manna <animesh.manna@xxxxxxxxx> >>>> >>>>>>>>Signed-off-by: Vathsala Nagaraju <vathsala.nagaraju@xxxxxxxxx> >>>> >>>>>>>>--- >>>> >>>>>>>> drivers/gpu/drm/i915/intel_csr.c | 9 +++++++++ >>>> >>>>>>>> 1 file changed, 9 insertions(+) >>>> >>>>>>>> >>>> >>>>>>>>diff --git a/drivers/gpu/drm/i915/intel_csr.c b/drivers/gpu/drm/i915/intel_csr.c >>>> >>>>>>>>index ba1ae03..682cc26 100644 >>>> >>>>>>>>--- a/drivers/gpu/drm/i915/intel_csr.c >>>> >>>>>>>>+++ b/drivers/gpu/drm/i915/intel_csr.c >>>> >>>>>>>>@@ -252,6 +252,15 @@ void intel_csr_load_program(struct drm_device *dev) >>>> >>>>>>>> return; >>>> >>>>>>>> } >>>> >>>>>>>>+ /* >>>> >>>>>>>>+ * Dmc will restore the csr the program except DC9, cold boot, >>>> >>>>>>>>+ * warm reset, PCI function level reset, and hibernate/suspend. >>>> >>>>>>>>+ * This condition will help to check if csr address space is reset/ >>>> >>>>>>>>+ * not loaded. >>>> >>>>>>>>+ */ >>>> >>>>>>>Atm we call this from driver load and resume, which doesn seem to cover >>>> >>>>>>>all the cases you mention in the comment. Should this be a WARN_ON >>>> >>>>>>>instead? Or do we have troubles in our init sequence where we load too >>>> >>>>>>>many times? >>>> >>>>>>Yes, the above statement taken from bspec to describe about the special cases dmc will not restore the firmware. >>>> >>>>>>Agree, In our cases cold boot and hibernate/suspend mainly we need to load the firmware again, so in my >>>> >>>>>>second sentence I wanted to comment mainly regarding this condition check added for suspend-hibernate(reset) >>>> >>>>>>and cold boot(not loaded). >>>> >>>>>> >>>> >>>>>>Anyways the same api later can be used to load the firmware from anywhere, so my intention to check firmware loaded or not. >>>> >>>>>>If already loaded then not to overwrite the csr address space to maintain the dc5/dc6 counter value. >>>> >>>>>> >>>> >>>>>>Can the below comment more clear to you. >>>> >>>>>> >>>> >>>>>> /* >>>> >>>>>> * Dmc will restore the csr the program except DC9, cold boot, >>>> >>>>>> * warm reset, PCI function level reset, and hibernate/suspend. >>>> >>>>>> * If firmware is restored by dmc then no need to load again which >>>> >>>>>> * will keep the dc5/dc6 counter exposed by firmware. >>>> >>>>>> */ >>>> >>>>>> >>>> >>>>>>No issue in init sequence. >>>> >>>>>That seems to still cover all the callers of the function afaics - we do >>>> >>>>>pci resets over suspend resume unconditionally. So I still don't >>>> >>>>>understand where exactly we try to load the dmc firmware in i915.ko when >>>> >>>>>it's already loaded. >>>> >>>>During resume intel_csr_load_program() will be called from >>>> >>>>intel_runtime_resume(). >>>> >>>> >>>> >>>>intel_runtime_resume()-> skl_resume_prepare()-> intel_csr_load_program() >>>> >>>> >>>> >>>>During Pc10 entry testing I can see dmc is restoring back the firmware always, >>>> >>>>but as you mentioned pci-reset can happen unconditionally, but still then >>>> >>>>also during resume intel_runtime_resume() will be called and based on >>>> >>>>register read of csr-base-address firmware loading will happen. >>>> >>>But in your comment you're saying it won't get restored in case of dc9 and >>>> >>>suspend. So that seems to mismatch what you're saying here (and what the >>>> >>>commit message says) and what the code does. And this function here is >>>> >>>called for resume after suspend/hibernate only. >>>> >>pc10 entry explanation I told is for skylake. dc9 in skylake is not possible. >>>> >>I think you are confusing between dc6 and dc9. Pc10 can be achieved by >>>> >>entering into dc6 (not dc9) for skylake. dc9 is the lowest possible state >>>> >>for broxton which is not present for skylake. >>>> >I have no idea at all about different pc levels on skl. What I'm talking >>>> >about is system suspend/resume and driver load, which are the places this >>>> >function gets called. At least afaics. >>>> > >>>> >>Here intel_csr_load_program() will be used for both skylake and broxton, and instruction >>>> >>execution flow will be different in case of suspend/resume which I think is confusing >>>> >>you. >>>> >That seems like really important information. What's different on bxt? >>>> >These are the kind of details you should explain in the commit message ... >>>> > >>>> >>I am ready explain you in detail. It will be good if we discuss specific use-case scenario >>>> >>and itz software design for specific platform. Another point - as dmc related code for >>>> >>broxton is not merged better first we close design for skylake. Now, I have added dc9 >>>> >>description in comment thinking of future. If you want I can remove for now and later >>>> >>can add in bxt patch series for enabling dmc. Will wait for your reply. >>>> >This question here isn't about the overall design and how to handle power >>>> >wells in skl/bxt. That's a separate discussion and tracked somewhere else. >>>> >I'm really just confused about when exactly we need to reload to firmware, >>>> >and why we need a runtime check for that. Normally we should know when to >>>> >reload the firmware and just either reload or not, without checking hw >>>> >state. And I don't like checking for hw state since at least in the past >>>> >that kind of code ended up being fragile - it's an illusion that it does >>>> >the right thing no matter what, since often there's other tricky ordering >>>> >constraints. And if you have automatic duct-tape like then no one will >>>> >ever spot those other, harder to spot issues, until an expensive customer >>>> >escalation happens. >>>> > >>>> >So what I want to know here is: >>>> >- When exactly do we need to reload dmc firmware. >>>> In skl, during driver load first time we load the firmware, during normal >>>> suspend-resume (dc6 entry/exit) >>>> no need to reload the firmware again as dmc will take care of it. But during >>>> suspend/hibernation >>>> dmc will not restore the firmware. In that case driver need to reload it >>>> again. I do not know >>>> how to differentiate pm-suspend and suspend-hibernation and thought both the >>>> cases >>>> intel_runtime_resume() will be called where we can check the h/w state and >>>> reload the >>>> firmware if dmc is not restored. >>>> >>>> In bxt, during driver load first time we load the firmware, during normal >>>> suspend-resume >>>> display engine will enter into dc9 and dmc will not restore the firmware. So >>>> every >>>> suspend-resume we need to reload the firmware. >>>> >- What exactly is the reason why we can't make that decision statically in >>>> > the code (by calling csr_load at the right spots). >>>> As I mentioned before in case of skylake can we differentiate between >>>> "resume from pm-suspend" with "resume from suspend-hibernation" inside >>>> driver? >>>> >>>> In case of broxton, every time we need to reload, so we can decide >>>> statically. >>> >>> Of course we can differentiate between all the different resume paths, and >>> we also have a per-platform split to take care of bxt vs. skl. And there >>> are actually 3 different resume paths: >>> >>> - runtime PM resume. This calls the runtime_resume hook. It sounds like on >>> skl we should _not_ load the csr firmware, but on bxt we should load it. >>> This can be fixed by removing the intel_csr_load_program call from >>> skl_resume_prepare. >>> - resume from hibernate-to-disk (i.e. system completely off, state stored >>> on the swap partition) is done by calling the thaw callbacks. >>> - resume from suspend-to-mem (i.e. system in low-power with only memory >>> in self-refresh, all state stored in memory) is done by calling the >>> resume callbacks. >>> >>> For i915 we use unified handlers in our dev_pm_ops for both thaw and >>> resume, but it sounds like that won't be a problem for skl/bxt since we >>> need to reload the csr firmware in all cases. Although I'm not perfectly >>> sure since you don't explain what kind of resume you mean exactly (since >>> you don't use the linux names for them). >>> >>> Anyway it sounds like we can replace this patch by one where we remove >>> that errornous csr load call from skl runtime pm resume and that's all. >>> But I suggest to make sure we get this right we keep the check you're >>> adding here, but wrap it in a WARN_ON. Then we'll get a backtrace when >>> this is going wrong again. Like this: >>> >>> if (WARN_ON(csr_loaded_already())) >>> return; >>> >>> Also when redoing the commits please explain in detail what exactly are >>> the requirements like you've done above, but please use the standard linux >>> names, i.e. "runtime PM" and "hibernate-to-disk" and "suspend-to-mem". >> >> Ok hooray there's more suspend-to-something things I've totally missed: >> - suspend-to-idle (done by cat freeze > /sys/power/state) and >> - suspend (done by cat suspend > /sys/power/state) >> >> And apparently there's really no way to drivers to tell them apart. >> Rafael, is there really no way for drivers to take different paths for >> these 3 suspend cases? I tried grepping for PM_SUSPEND_ON/STANDY/MEM >> and didn't spot anything. >> >> Also we're completely missing test coverage for that in igt. That is >> something that needs to be fixed asap (yet another case of >> combinatorial explosion in igt tests, yay). And at least one of those >> suspend-to-idle testcase better be in the BAT. >> -Daniel >> -- >> Daniel Vetter >> Software Engineer, Intel Corporation >> +41 (0) 79 365 57 48 - http://blog.ffwll.ch > > > > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
