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. 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
