On Tue, 2019-12-03 at 10:31 -0600, Jeremy Linton wrote: > Hi, > > On 11/26/19 3:19 AM, Nicolas Saenz Julienne wrote: > > From: Jim Quinlan <james.quinlan@xxxxxxxxxxxx> > > > > This adds a basic driver for Broadcom's STB PCIe controller, for now > > aimed at Raspberry Pi 4's SoC, bcm2711. > > > > Signed-off-by: Jim Quinlan <james.quinlan@xxxxxxxxxxxx> > > Co-developed-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx> > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx> > > > > --- > > > > Changes since v2: > > - Correct rc_bar2_offset sign > > - Invert IRQ clear and masking in setup code > > - Use bitfield.h, redo all register ops while keeping the register > > names intact > > - Remove all SHIFT register definitions > > - Get rid of all _RB writes > > - Get rid of of_data > > - Don't iterate over inexisting dma-ranges > > - Add comment regarding dma-ranges validation > > - Small cosmetic cleanups > > - Fix license mismatch > > - Set driver Kconfig tristate > > - Didn't add any comment about the controller not being I/O coherent > > for now as I wait for Jeremy's reply > > I guess its fine.. In answer to the original query. It seems that this > PCIe bridge requires explicit cache operations for DMA from PCIe > endpoints. This wasn't obvious to me at first reading because I was > assuming the custom DMA ops were strictly to deal with the stated DMA > limits. Thanks, I now see what you meant. > So if you end up respinning, it still might be worthy mentioning > somewhere that this is a non-coherent PCIe implementation. I still hold > much of my original reservations about pieces of this driver. > Particularly, how it might look if someone wanted to boot the RPi using > ACPI on linux. But, I was shown a clever bit of AML recently, which > solves those problems for the RPi and the attached XHCI. I don't know much about ACPI, but ultimately if you're booting trough ACPI, you're unlikely to use device-tree at all, right? And if you where and this driver clashed with your ACPI implementation you'd simply have to disable it on the device-tree. > So, given how much time I've looked at the root port configuration/etc > sections of this driver and I've not found a serious bug: > > Reviewed-by: Jeremy Linton <jeremy.linton@xxxxxxx> Thanks! Regards, Nicolas
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