On Sun, May 13, 2012 at 11:46 PM, Richard Yang <weiyang@xxxxxxxxxxxxxxxxxx> wrote: > On Sun, May 13, 2012 at 10:40:41PM -0700, Yinghai Lu wrote: >>On Sun, May 13, 2012 at 6:55 PM, Richard Yang >><weiyang@xxxxxxxxxxxxxxxxxx> wrote: >>> On Mon, Apr 23, 2012 at 03:46:03PM -0400, Don Dutile wrote: >>>>On 04/22/2012 11:52 AM, Richard Yang wrote: >>>>>All, >>>>> >>>>>I am reading the pci_scan_bridge() and not sure what will happen in >>>>>following situation. >>>>> >>>>>Suppose the kernel is not passed the pci=assign-busses. >>>>> >>>>>Below is a picture about the pci system. >>>>> >>>>> +-------+ >>>>> | | root bridge(0,255) >>>>> +---+---+ >>>>> | Bus 0 >>>>> -----+-----------+------------------------------+-- >>>>> | | >>>>> | | >>>>> | | >>>>> +----+----+ +-----+-----+ >>>>> | | B1(1,15) | |B2(16,28) >>>>> +----+----+ +-----+-----+ >>>>> | Bus 1 | Bus 16 >>>>> -----+----------------------- ----------+---------------- >>>>> | >>>>> +----+----+ >>>>> | | B3 >>>>> +---------+ >>>>> >>>>>Suppose B1 and B2 works fine with the BIOS, which get the right bus >>>>>number and range. >>>>> >>>>>B3 does not works fine with the BIOS, which doesn't get the bus number. >>>>> >>> Take my original question. >>> >>> B3 doesn't get the bus number, which its parent doesn't have free bus >>> number and there is no gap between B1 and B2. >>> >>> So in this case, the probe_resource() can't find bus number for B3. >>> Then cause pci_bridge_probe_busn_res() return non-zero. >>> >>> Then B3 couldn't work fine? >> >>B3 is on Bus 1? B3 is the one of bridges on Bus1? > No, I omit other bridges on Bus#1. > They will occupy bus number 2-15, which is calculated by BIOS and set to > bridge's configuration space. with that new condition, probe_resource will return zero. for those kind of case: 1. use echo 1 > /sys .../remove to remove devices under Bridge2. 2. use setpci to change bus register of bridge2 to move high to make more space for bridge 1. 3. rescan bridge 1 and bridge 2. Yinghai -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
