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Thu, 28 Jul 2022 10:17:48 -0700 (PDT) MIME-Version: 1.0 References: <20220728131608.31901-1-lukasz.bartosik@semihalf.com> In-Reply-To: From: =?UTF-8?Q?=C5=81ukasz_Bartosik?= Date: Thu, 28 Jul 2022 19:17:37 +0200 Message-ID: Subject: Re: [PATCH v1] thunderbolt: fix PCI device class after powering up To: Greg KH Cc: Andreas Noever , Michael Jamet , Mika Westerberg , Yehezkel Bernat , linux-usb@vger.kernel.org, upstream@semihalf.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org > > On Thu, Jul 28, 2022 at 06:31:47PM +0200, =C5=81ukasz Bartosik wrote: > > > > > > On Thu, Jul 28, 2022 at 03:16:08PM +0200, Lukasz Bartosik wrote: > > > > From: =C5=81ukasz Bartosik > > > > > > > > A thunderbolt > > > > lspci -d 8086:9a1b -vmmknn > > > > Slot: 00:0d.2 > > > > Class: System peripheral [0880] > > > > Vendor: Intel Corporation [8086] > > > > Device: Tiger Lake-LP Thunderbolt 4 NHI #0 [9a1b] > > > > > > > > presents itself with PCI class 0x088000 after Chromebook boots. > > > > lspci -s 00:0d.2 -xxx > > > > 00:0d.2 System peripheral: Intel Corporation Tiger Lake-LP Thunderb= olt 4 > > > > NHI #0 (rev 01) > > > > 00: 86 80 1b 9a 00 00 10 00 01 00 80 08 00 00 00 00 > > > > ... > > > > > > > > However after thunderbolt is powered up in nhi_probe() > > > > its class changes to 0x0c0340 > > > > lspci -s 00:0d.2 -xxx > > > > 00:0d.2 System peripheral: Intel Corporation Tiger Lake-LP Thunderb= olt 4 > > > > NHI #0 (rev 01) > > > > 00: 86 80 1b 9a 06 04 10 00 01 40 03 0c 00 00 00 00 > > > > ... > > > > > > > > which leaves pci_dev structure with old class value > > > > cat /sys/bus/pci/devices/0000:00:0d.2/class > > > > 0x088000 > > > > > > > > This fix updates PCI device class in pci_dev structure after > > > > thunderbolt is powered up. > > > > > > > > Fixes: 3cdb9446a117 ("thunderbolt: Add support for Intel Ice Lake") > > > > Signed-off-by: =C5=81ukasz Bartosik > > > > --- > > > > drivers/thunderbolt/nhi_ops.c | 5 +++++ > > > > 1 file changed, 5 insertions(+) > > > > > > > > diff --git a/drivers/thunderbolt/nhi_ops.c b/drivers/thunderbolt/nh= i_ops.c > > > > index 96da07e88c52..6a343d7e3f90 100644 > > > > --- a/drivers/thunderbolt/nhi_ops.c > > > > +++ b/drivers/thunderbolt/nhi_ops.c > > > > @@ -160,12 +160,17 @@ static int icl_nhi_suspend_noirq(struct tb_nh= i *nhi, bool wakeup) > > > > > > > > static int icl_nhi_resume(struct tb_nhi *nhi) > > > > { > > > > + u32 class; > > > > int ret; > > > > > > > > ret =3D icl_nhi_force_power(nhi, true); > > > > if (ret) > > > > return ret; > > > > > > > > + /* Set device class code as it might have changed after power= ing up */ > > > > + pci_read_config_dword(nhi->pdev, PCI_CLASS_REVISION, &class); > > > > + nhi->pdev->class =3D class >> 8; > > > > > > What about the revision field, why not set that as well: > > > nhi->pdev->revision =3D class & 0xff; > > > > > > If the value is overwritten for 3 of the bytes, why not the 4th? > > > > Fair point but I observed class change, revision stayed the same. > > I read class and revision before and after icl_nhi_force_power() with > > pci_read_config_dword(nhi->pdev, PCI_CLASS_REVISION, &class); > > It changed from 0x8800001 -> 0xc034001 > > > > > Also this feels odd, what is changing the bytes here? Why only the > > > class? What else changed and what caused it? > > > > I compared 64 bytes of config space before and after modprobing > > thunderbolt module > > Before modprobe > > lspci -s 00:0d.2 -x > > 00:0d.2 System peripheral: Intel Corporation Tiger Lake-LP Thunderbolt > > 4 NHI #0 (rev 01) > > 00: 86 80 1b 9a 00 00 10 00 01 00 80 08 00 00 00 00 > > 10: 04 00 a0 80 02 00 00 00 04 80 a4 80 02 00 00 00 > > 20: 00 00 00 00 00 00 00 00 00 00 00 00 22 22 11 11 > > 30: 00 00 00 00 80 00 00 00 00 00 00 00 ff 01 00 00 > > > > After modprobe > > lspci -s 00:0d.2 -x > > 00:0d.2 System peripheral: Intel Corporation Tiger Lake-LP Thunderbolt > > 4 NHI #0 (rev 01) > > 00: 86 80 1b 9a 06 04 10 00 01 40 03 0c 00 00 00 00 > > 10: 04 00 a0 80 02 00 00 00 04 80 a4 80 02 00 00 00 > > 20: 00 00 00 00 00 00 00 00 00 00 00 00 22 22 11 11 > > 30: 00 00 00 00 80 00 00 00 00 00 00 00 ff 01 00 00 > > > > The diff is in class 00 80 08 -> 40 03 0c > > and command 00 00 -> 06 04 > > > > The value 40 03 0c is defined as PCI_CLASS_SERIAL_USB_USB4 in > > drivers/thunderbolt/nhi.h > > > > I think the device itself changed the class because I tried to change > > class value with setpci command and it seems to be read-only. > > Wait huh? You can't change the class of a device in the configuration, > that is read-only. Sorry my statement might have been confusing. I tried to change class value with setpci as an experiment to make sure it is read-only and it is ro. > So this is working properly without this patch, right? After thunderbolt is probed its class changes from 00 80 08 -> 40 03 0c and without this patch thunderbolt's pci_dev struct is left holding old class value 00 80 08 which is not correct. Thanks, Lukasz > thanks, > > greg k-h