One thing to try: swap the cards between the laptop and the netbook, to check if the differences depend on the card or the system. On Wed, May 5, 2010 at 8:03 PM, Larry Finger <Larry.Finger@xxxxxxxxxxxx> wrote: > I received the netbook from John last Saturday. It took a while to get > it integrated into my network as this is my first Fedora system, but I > now have some results to report. > > I loaded wl logging both MMIO and PCI configuration register reads and > writes. The two types are now interleaved. The latter are logged with > trace_printk() calls. Note: There is a bug in current kernel code that > keeps these calls from being logged. Thanks to Stephen Rostedt for > sorting out this problem. > > Both systems have the same core sequence and the same revisions. The > cores in order are ChipCommon rev 0x16, IEEE 802.11 rev 0x0F, PCMCIA rev > 0x0A, and PCI-E rev 0x09. > > I now know for certain that the netbook has an SPROM at offset 0x800. > Trying to read at offset 0x1000, which is the SPROM location in the > laptop, locks the machine, thus we need to determine the SPROM location > without reading 0x1000. > > Fortunately, the wl driver reads and writes PCI configuration space from > the Linux shim code, not from the binary blob, thus these operations can > be traced. > > The _only_ differences between the laptop and netbook operations between > startup and the reading of the SPROM are as follows: > > Register Laptop Netbook Explanation > > PCI 0x0C 0x10 0x08 Cache Line Size > PCI 0x04 0x00100106 0x001000006 Command Features [1] > Core 0 0x2C 0x10 0x12 Chip Status Reg [2] > Core 3 0x800 0x2801 0x3801 On laptop 0x3801 written > Core 3 0x280a 0x6dbe 0xedbe On laptop 0xedbe written > > The code then switches to Core 1 (802.11) and begins reading SPROM. On > the laptop, it reads from 0x1000 and does a try at the smaller size > SPROM, then switches to the larger size, just as ssb does. On the > netbook, it immediately reads the larger size at offset 0x800. > > I have not yet looked closely at the differences between wl and ssb, but > I did note one difference. In wl, bits 0xFF00 are cleared in PCI > register 0x40. The only thing I could find is this code fragment from > ipw2100 and ipw2200: > > /* We disable the RETRY_TIMEOUT register (0x41) to keep > * PCI Tx retries from interfering with C3 CPU state */ > pci_read_config_dword(pdev, 0x40, &val); > if ((val & 0x0000ff00) != 0) > pci_write_config_dword(pdev, 0x40, val & 0xffff00ff); > > Larry > > [1] The Wikipedia article on PCI configuration space says that this is a > bitmask of features that can be enabled/disabled. I have no explanation > of the details. > > [2] This extra bit looks most promising of all the differences. It is > the bit involved in the is_sprom_available() routine for the 4315 device > in the Broadcom driver that has been reverse engineered; however, the > definition must have changed as that code would say there is no SPROM, > which is clearly untrue. > -- Vista: [V]iruses, [I]ntruders, [S]pyware, [T]rojans and [A]dware. :-) -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
