[PATCH v3] PCI: mvebu: Setup BAR0 in order to fix MSI

[Thomas Petazzoni]

On Tue, 23 Jun 2020 09:03:35 +0300
Shmuel Hazan <sh at tkos.co.il> wrote:

> According to the Armada XP datasheet, section 10.2.6: "in order for
> the device to do a write to the MSI doorbell address, it needs to write
> to a register in the internal registers space".
> 
> As a result of the requirement above, without this patch, MSI won't
> function and therefore some devices won't operate properly without
> pci=nomsi.
> 
> This requirement was not present at the time of writing this driver
> since the vendor u-boot always initializes all PCIe controllers
> (incl. BAR0 initialization) and for some time, the vendor u-boot was
> the only available bootloader for this driver's SoCs (e.g. A38x,A37x,
> etc).
> 
> Tested on an Armada 385 board on mainline u-boot (2020.4), without
> u-boot PCI initialization and the following PCIe devices:
>         - Wilocity Wil6200 rev 2 (wil6210)
>         - Qualcomm Atheros QCA6174 (ath10k_pci)
> 
> Both failed to get a response from the device after loading the
> firmware and seem to operate properly with this patch.
> 
> Signed-off-by: Shmuel Hazan <sh at tkos.co.il>

Acked-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>

Thanks a lot for the research and the different iterations!

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com