On Tue, May 15, 2012 at 10:32:46AM -0700, Yinghai Lu wrote: >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. So these steps is done after boot up and user find B3 doesn't work? > >Yinghai -- Richard Yang Help you, Help me -- 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
