Hello Bjorn, > -----Original Message----- > From: linux-hotplug-owner@xxxxxxxxxxxxxxx [mailto:linux-hotplug- > owner@xxxxxxxxxxxxxxx] On Behalf Of Bjorn Helgaas > Sent: Tuesday, February 11, 2014 4:35 PM > To: Rajat Jain > Cc: Rajat Jain; linux-pci@xxxxxxxxxxxxxxx; linux hotplug mailing; Kenji > Kaneshige; Yijing Wang; Greg KH; Tom Nguyen; Kristen Accardi; Rajat > Jain; Guenter Roeck > Subject: Re: [PATCH] pciehp: Acknowledge the spurious "cmd completed" > event. > > On Mon, Nov 25, 2013 at 07:03:11PM +0000, Rajat Jain wrote: > > Hello, > > > > > > On a different note, I feel there is still a need to apply my > > > > original > > > patch. There is still an open problem in case of spurious interrupts > > > (or in any case where the condition "if (slot_status & > PCI_EXP_SLTSTA_CC)" > > > becomes true in pcie_write_cmd()). That is because once that > > > happens, we never clear that interrupt, and no further hotplug > > > interrupts shall be received unless we do that. > > > > > > I agree this is an issue and we should address it somehow. My > > > hesitation is just that I'd prefer to do some more aggressive > > > restructuring rather than apply a point fix. For example: > > > > OK, I'll attempt to fix it that way when I get time. > > > > > > > > - We currently look at PCI_EXP_SLTSTA_CC in pcie_isr(), > > > pcie_poll_cmd(), and pcie_write_cmd(). I think it would be better > > > to look at it only in pcie_isr(). > > > > > > - I don't think pcie_poll_cmd() should exist at all; we should poll > > > by calling pcie_isr() instead. > > > > > > - We need pcie_write_cmd(), but I think the way it waits is > backwards. > > > Currently we issue the command, then wait for it to complete. I > > > think we should issue the command, note the current time, and return > > > without waiting. The *next* time we need to issue a command, we can > > > wait for completion of the previous one (or timeout) if necessary. > > > > > > But maybe we need the point fix in the interim, especially if > > > anybody can actually produce the scenario you mention. > > > > Ok. > > This patch is still in patchwork, but I've lost track of where we are. > Did you resolve this in the series that I just applied, or is it still > an outstanding issue? No, I did not solve it. It is still an outstanding issue. So far I am using your patch to overcome this: http://www.spinics.net/lists/hotplug/msg05830.html I'll just attempt to conclude the status on this issue so that you can make the decision on the course of action. IMHO there are 2 independent issues that we discussed in this thread: 1) PCIe compliant HW (that generates cmd completed interrupts at every write of Slot_ctrl register) being penalized with 1 second delay during the boot up. Your patch solves this. 2) If there is a genuine spurious interrupt, it does not get acknowledged. I had originally posted a patch for THIS problem. http://www.spinics.net/lists/hotplug/msg05815.html You had indicated that you would rather want a bigger restructuring of the driver to solve (2). My observation: MY problem (in my setup) is not seen if I use either of the patches (yours or mine). My opinion: I think my patch solves (2) but might not solve (1) for all corner cases. Also your patch solves (1) but may not solve (2) for all corner cases -Thus we should probably solve both of these problems individually. Thanks, Rajat > > Bjorn > -- > To unsubscribe from this list: send the line "unsubscribe linux-hotplug" > in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo > info at http://vger.kernel.org/majordomo-info.html > ��.n��������+%������w��{.n�����{��-�[��)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
