Hi Alan, On Thursday, January 10, 2019, Alan wrote: > > On Thu, 10 Jan 2019, Ran Wang wrote: > > > Hi Alan, > > > > > -----Original Message----- > > > From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > > > Sent: Wednesday, January 09, 2019 23:14 > > > To: Ran Wang <ran.wang_1@xxxxxxx> > > > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; linux- > > > usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > > > Subject: RE: [PATCH 2/3] usb: ehci: fsl: Update register accessing > > > for > > > arm/arm64 platforms > > > > > > On Wed, 9 Jan 2019, Ran Wang wrote: > > > > > > > > Why do you change this writel() into iowrite32be() but leave > > > > > other instances of writel() unchanged? Was this a mistake? > > > > > > > > Yes, I didn't notice there are other writel() used in this file. > > > > However, as I know, on both powerpc and arm SoC, EHCI FSL IP's > > > > memory mapped register block is always Big-endian, so I'd like to > > > > replace all > > > > writel() with iowrite32be() in this file. Is it necessary? > > > > > > > > Or I just replace them with ehci_writel() and select > > > CONFIG_USB_EHCI_BIG_ENDIAN_MMIO? > > > > > > That should work okay. ehci_fsl_setup() sets ehci->big_endian_desc > > > and > > > ehci->big_endian_mmio according to the platform data, so you just > > > ehci->have > > > to make sure the platform data is initialized correctly. > > > > > OK, so I should not change writel() into iowrite32be() at that place > > you mentioned, and still using iowrite32be()/ioread32be() to replace > > clrsetbits_be32(), am I right? > > Actually, I think it would be good to use ehci_writel() and > ehci_readl() everywhere except in fsl_ehci_drv_probe(). > > But if you prefer to use iowrite32be() and ioread32be() instead, that's > probably okay. (However, it won't work if anyone ever produces a little- > endian version of the IP.) Got it, I'll verify with ehci_readl() then work out the v2 patch if pass. Thanks for advice. Regards, Ran
