[PATCH] i.MX6 PCIe: Fix imx6_pcie_deassert_core_reset() polarity

[Tim Harvey]

On Tue, Mar 29, 2016 at 9:44 AM, Roberto Fichera <kernel at tekno-soft.it> wrote:
> On 03/29/2016 06:40 PM, Tim Harvey wrote:
>> On Tue, Mar 29, 2016 at 9:13 AM, Roberto Fichera <kernel at tekno-soft.it> wrote:
>>> On 03/29/2016 05:10 PM, Tim Harvey wrote:
>>>> Arnd,
>>>>
>>>> Right, on the IMX the MSI interrupt is GIC-120 which is also the
>>>> legacy INTD and I do see that if I happen to put a radio in a slot
>>>> where due to swizzling its pin1 becomes INTD (GIC-120) the interrupt
>>>> does fire and the device works. Any other slot using GIC-123 (INTA),
>>>> GIC-122 (INTB), or GIC-121 (INTC) never fires so its very possible
>>>> that something in the designware core is masking out the legacy irqs.
>>>> I would also think this was something IMX specific, but I really don't
>>>> see any codepaths in pci-imx6.c that would cause that: a driver
>>>> requesting a legacy PCI would get a GIC interrupt which is handled by
>>>> the IMX6 gpc interrupt controller.
>>>>
>>>> Any dra7xxx, exynos, spear13xx, keystone, layerscape, hisi, qcom SoC
>>>> users of designware PCIe core out there that can verify PCI MSI and
>>>> legacy are both working at the same time?
>>>>
>>>> Lucas is the expert here and I believe he has the documentation for
>>>> the designware core that Freescale doens't provide with the IMX6
>>>> documentation so hopefully he can provide some insight. He's the one
>>>> that has authored all the MSI support and has been using it.
>>>>
>>>> I typically advise our users to 'not' enable MSI because
>>>> architecturally you can spread 4 distinct legacy irq's across CPU's
>>>> better than a single shared irq.
>>> Don't know if I'm facing similar problem, however devices connected in miniPCI slot behind
>>> a PCIe-to-PCI bridge (MSI is disabled) using INTA all is working ok, including shared IRQ.
>>> In case of INTB will not work, and the GIC irq quite often get stuck.
>>>
>> Roberto,
>>
>> What board/platform is this and what does /proc/interrupts look like?
>
> It's a custom board
>
> root at voneus-janas-imx6q:~# cat /proc/interrupts
>            CPU0       CPU1       CPU2       CPU3
>  16:        936        637       2057        938       GIC  29 Edge      twd
>  17:          0          0          0          0       GPC  55 Level     i.MX Timer Tick
>  22:        247          0          0          0       GPC  26 Level     2020000.serial
>  34:          0          0          0          0  gpio-mxc   6 Edge      Factory Reset Button
> 267:          0          0          0          0       GPC  49 Level     imx_thermal
> 272:          0          0          0          0       GPC  19 Level     rtc alarm
> 278:          0          0          0          0       GPC   2 Level     sdma
> 281:        361          0          0          0       GIC 150 Level     2188000.ethernet
> 282:          0          0          0          0       GIC 151 Level     2188000.ethernet
> 283:       2882          0          0          0       GPC  25 Level     mmc0
> 284:         95          0          0          0       GPC  37 Level     21a4000.i2c
> 290:      36546          0          0          0       GPC 123 Level     PCIe PME, b4xxp
> 291:          2          0          0          0       GIC 137 Level     2101000.jr0
> 292:          0          0          0          0       GIC 138 Level     2102000.jr1
> IPI0:          0          0          0          0  CPU wakeup interrupts
> IPI1:          0          0          0          0  Timer broadcast interrupts
> IPI2:       1642       1038       1626       1781  Rescheduling interrupts
> IPI3:         95         95        122        119  Function call interrupts
> IPI4:          3          0          2          0  Single function call interrupts
> IPI5:          0          0          0          0  CPU stop interrupts
> IPI6:          0          0          0          0  IRQ work interrupts
> IPI7:          0          0          0          0  completion interrupts
> Err:          0
>
>
>>
>> This sounds like what would happen if the downstream interrupts on the
>> PCIe-to-PCI bridge are not mapped properly as was the case with a
>> board I support (in which case I had to work out a bootloader fixup
>> that placed a non-standard interrupt-map in the device-tree for the
>> bridge). What bridge are you using?
>
> PCIe-to-PCI bridge is a Ti XIO2001 where we are using INTA/B only wired 1:1
>

Roberto,

That's right, we've talked about your bridge on IMX community.

I don't see anything in your proc/interrupts other than GPC 123 - you
probably only had one device populated when you did that. Put devices
in all for slots then show me 'cat /proc/interrupts' as well as 'lspci
-vv' (so that I can see what interrupt was given to pin1 and what
interrupt that maps to on the IMX6).

Check your XIO2001 routing and insure the following for proper IRQ mapping:
Slot12: IDSEL A28: socket INTA = XIO2001 INTA
Slot13: IDSEL A29: socket INTA = XIO2001 INTB
Slot14: IDSEL A30: socket INTA = XIO2001 INTC
Slot15: IDSEL A31: socket INTA = XIO2001 INTD

The relationship between slot number of IDSEL is based on the PCI
specification. The XIO2001 int mapping to socket mapping is based on
Table 2 in the XIO2001 implementation guide. In my case what the
hardware designer flipped the IDSEL mappings above such that slot12's
idsel was hooked to A31 (so it was really slot15) etc, which created a
non-standard mapping that required what ended up being a very time
consuming and difficult to figure out software fixup (to say the
least).

Tim