HI Andy,
On Wed, 8 Apr 2020 at 10:58, Andy Shevchenko andriy.shevchenko@linux.intel.com wrote:
On Tue, Apr 07, 2020 at 08:57:20PM -0600, Simon Glass wrote:
Hi Andy,
On Fri, 3 Apr 2020 at 05:22, Andy Shevchenko andriy.shevchenko@linux.intel.com wrote:
On Mon, Mar 30, 2020 at 05:12:46PM -0600, Simon Glass wrote:
At present if reading a BAR returns 0xffffffff (e.g. the device is not present) then the value is masked and a different value is returned. This makes it harder to detect the problem when debugging.
The above ('the device is not present') is actually not correct. BAR is not mandatory register and detection is described in PCI spec.
What change are you suggesting here? I suggest 'not present' as an example of why this might happen.
I suggest to follow PCI spec. Thus, the code below is fragile and working by luck.
I don't know what you are suggesting. This allows an error to be reported in the common case and helps people discover mistakes in the driver flow. What is your suggestion?
Rgards, SImon
To get device presence one may have check Vendor ID / Device ID pair rather then BAR.
Update the function to avoid masking in this case.
Signed-off-by: Simon Glass sjg@chromium.org Reviewed-by: Bin Meng bmeng.cn@gmail.com Reviewed-by: Wolfgang Wallner wolfgang.wallner@br-automation.com
Changes in v3: None Changes in v2: None
drivers/pci/pci-uclass.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c index ceb64517047..d2e10d6868a 100644 --- a/drivers/pci/pci-uclass.c +++ b/drivers/pci/pci-uclass.c @@ -1213,7 +1213,14 @@ u32 dm_pci_read_bar32(const struct udevice *dev, int barnum)
bar = PCI_BASE_ADDRESS_0 + barnum * 4; dm_pci_read_config32(dev, bar, &addr);
if (addr & PCI_BASE_ADDRESS_SPACE_IO)
/** If we get an invalid address, return this so that comparisons with* FDT_ADDR_T_NONE work correctly*/if (addr == 0xffffffff)return addr;else if (addr & PCI_BASE_ADDRESS_SPACE_IO) return addr & PCI_BASE_ADDRESS_IO_MASK; else return addr & PCI_BASE_ADDRESS_MEM_MASK;-- 2.26.0.rc2.310.g2932bb562d-goog
-- With Best Regards, Andy Shevchenko
Regards, Simon
-- With Best Regards, Andy Shevchenko