On 03/16/2016 10:33 PM, Tim Harvey wrote: > On Wed, Mar 16, 2016 at 7:19 AM, Fabio Estevam <festevam@xxxxxxxxx> wrote: >> Tim, >> >> On Tue, Mar 15, 2016 at 11:29 AM, Roberto Fichera <kernel@xxxxxxxxxxxxx> wrote: >>> On 03/15/2016 03:10 PM, Fabio Estevam wrote: >>>> On Tue, Mar 15, 2016 at 8:08 AM, Roberto Fichera <kernel@xxxxxxxxxxxxx> wrote: >>>> >>>>> Just to say that I've fixed the problem by asserting PERST before to drop PCIe refclk and enable >>>>> power down. PERST is finally released at the usual place. >>>> Excellent! Do you plan to submit a patch to fix this issue? >>> I don't know, in my case the problem was related to the XIO2001 that require PERST to be >>> asserted before to drop PCIe refclk as reported by its datasheet: >> Does your board detect XIO2001 bridge with kernel 4.4.x or do you also >> need something like Roberto's changes below? >> > Fabio, > > The board combination I have where an XIO2001 is connected directly to > an IMX6 is a bit different from Roberto's setup. In our configuration > the XIO2001 is on an 'expansion' board that its own local PCI clock > generation. So, in my case the XIO2001 always has a valid clock > before/during/after its reset. This is different from Roberto's > scenario. I do recall running into an issue with the XIO2001 on > another product with a different host controller that had to do with > noise on the clk prior to its reset being asserted so I am not too > surprised at what Roberto has found. > > I don't specifically see an issue with a change that asserts PCI_RST# > before the CLK gets enabled then de-asserts it after at least 100ms > has expired from clock enable - I think that actually follows the > specs wording closer than what we currently do (turning o the clock > prior to assert/de-assert reset). However I get very nervous at any > change to the IMX6 PCIe init. We have found it to be very finicky > because of the lack of a proper reset. > > Roberto, > > Did you require the changes regarding Gen2 negotiation? My > IMX6+XIO2001 links reliably at Gen1 which makes sense for that chip. You are right, I did all my tests again removing all applied changes related to Gen2 negotiation, and indeed the links goes up correctly at Gen1. > > Regards, > > Tim > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
