Am Donnerstag, den 13.12.2018, 12:34 +0000 schrieb Lorenzo Pieralisi: > On Thu, Dec 13, 2018 at 11:07:16AM +0100, Lucas Stach wrote: > > Am Donnerstag, den 13.12.2018, 09:57 +0000 schrieb Richard Zhu: > > > Hi Lucas: > > > > > > > -----Original Message----- > > > > > > From: Lucas Stach [mailto:l.st...@pengutronix.de] > > > > > > > > Sent: 2018年12月13日 17:19 > > > > > > > > To: Richard Zhu <hongxing....@nxp.com>; bhelg...@google.com; > > > > > > > > lorenzo.pieral...@arm.com; andrew.smir...@gmail.com > > > > > > > > Cc: linux-...@vger.kernel.org; > > > > > > > > linux-arm-ker...@lists.infradead.org; > > > > > > > > linux-kernel@vger.kernel.org > > > > Subject: Re: [v2] PCI: imx: make msi work without pcieportbus > > > > > > > > Hi Richard, > > > > > > > > Am Donnerstag, den 13.12.2018, 08:02 +0000 schrieb Richard Zhu: > > > > > MSI_EN of iMX PCIe RC would be asserted when PCIEPORTBUS driver is > > > > > selected. > > > > > Thus, the MSI works fine on iMX PCIe before. > > > > > Assert it unconditionally when MSI is supported. > > > > > Otherwise, the MSI wouldn't be triggered although the EP is present > > > > > and the MSIs are assigned. > > > > > > > > Thanks for digging into this issue. This seems like the right way > > > > forward. > > > > However, did you test this with devices using legacy IRQs? > > > > I.e. booting with "nomsi" on the kernel command line to see if legacy > > > > IRQs still > > > > work if this bit is set, or if we need to avoid setting this when the > > > > user > > > > explicitly requests to disable MSIs? > > > > > > > > Regards, > > > > Lucas > > > > > > > > > > [Richard Zhu] Thanks for your review. > > > The Legacy INTx is broken. > > > The MSI_EN bit shouldn't be asserted when the user explicitly requests to > > > disable MSIs. > > > > Okay, so this patch should be extended with a check for > > pci_msi_enabled() to see if the user explicitly want legacy IRQs. > > > > > BTW, regarding to Baruch's comments, it seems that all the > > > (IS_ENABLED(CONFIG_PCI_MSI) check in > > > the dwc host drivers are not required anymore, since the depends on > > > PCI_MSI_IRQ_DOMAIN, right? > > > > That's correct. This is mostly a historical artifact from the time when > > we were able to build without MSI support. Those checks could be > > cleaned up now that we depend on the MSI options. > > The question is whether we should really depend on PCI_MSI_IRQ_DOMAIN > option, should we ?
It certainly cuts down on the combinatorial space when testing those changes. IMHO this is a good thing, so as long as there is no compelling reason for making this dependency configurable I'm totally fine with keeping it the way it is now. Regards, Lucas
