[PATCH 2/3] pci: Make auto-config code a little more robust

[Stefan Roese]

Adding a few more PCI experts (Simon & Bin) to Cc.

On 03.01.21 23:06, Phil Sutter wrote:
> On my DS414, some PCI devices return odd values when probing BAR sizes.
> An obvious case is all-ones response, the Linux driver
> (drivers/pci/probe.c) catches those explicitly and a comment explains
> that either bit 0 or bit 1 must be clear (depending on MEM or IO type).
> Other BARs return e.g. 0xfff0000f or 0xfff00004 and thus manage to break
> size calculation due to the "middle" zeroes. Mitigate that copying more
> or less what Linux does and do a "find least bit set".
> 
> Signed-off-by: Phil Sutter <phil at nwl.cc>
> ---
>   drivers/pci/pci_auto.c | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/pci_auto.c b/drivers/pci/pci_auto.c
> index 3f46b7697d7ca..ea202b0e0959e 100644
> --- a/drivers/pci/pci_auto.c
> +++ b/drivers/pci/pci_auto.c
> @@ -47,16 +47,17 @@ void dm_pciauto_setup_device(struct udevice *dev, int bars_num,
>   			dm_pci_write_config32(dev, bar, 0xffffffff);
>   		dm_pci_read_config32(dev, bar, &bar_response);
>   
> -		/* If BAR is not implemented go to the next BAR */
> -		if (!bar_response)
> +		/* If BAR is not implemented (or invalid) go to the next BAR */
> +		if (!bar_response || bar_response == 0xffffffff)
>   			continue;
>   
>   		found_mem64 = 0;
>   
>   		/* Check the BAR type and set our address mask */
>   		if (bar_response & PCI_BASE_ADDRESS_SPACE) {
> -			bar_size = ((~(bar_response & PCI_BASE_ADDRESS_IO_MASK))
> -				   & 0xffff) + 1;
> +			bar_size = bar_response & PCI_BASE_ADDRESS_IO_MASK;
> +			bar_size &= ~(bar_size - 1);
> +
>   			if (!enum_only)
>   				bar_res = io;
>   

Reviewed-by: Stefan Roese <sr at denx.de>

Thanks,
Stefan