On Fri, Jul 16, 2021 at 4:07 PM Ralf Ramsauer <ralf.ramsauer@xxxxxxxxxxxxxxxxx> wrote: > On 14/07/2021 15:35, Andy Shevchenko wrote: > > On Wed, Jul 14, 2021 at 3:56 PM Ralf Ramsauer > > <ralf.ramsauer@xxxxxxxxxxxxxxxxx> wrote: > >> On 14/07/2021 08:54, Jiri Slaby wrote: > >>> On 13. 07. 21, 12:40, Andy Shevchenko wrote: > > > >>> Hmm, have you checked the commit which introduced the whitelist? > >>> > >>> Nevertheless, this needs to handled with care: while many 8250 devices > >>> actually claim to support MSI(-X) interrupts it should not be > >>> enabled be > >>> default. I had at least one device in my hands with broken MSI > >>> implementation. > >>> > >>> So better introduce a whitelist with devices that are known to support > >>> MSI(-X) interrupts. I tested all devices mentioned in the patch. > >>> > >>> > >>> You should have at least CCed the author for an input. > >> > >> Yep, back then I was testing three different 8250 pci cards. All of them > >> claimed to support MSI, while one really worked with MSI, the one that I > >> whitelisted. So I thought it would be better to use legacy IRQs as long > >> as no one tested a specific card to work with MSI. > > > > Can you shed a light eventually what those cards are? > So I found a no-name el-cheapo card that has some issues with MSI: Win Chip Head (WCH) > 18:00.0 Serial controller: Device 1c00:3253 (rev 10) (prog-if 05 [16850]) > > The card comes with two serial lines. It comes perfectly up, if I enable > it to use MSI in the whitelist: > > serial 0000:18:00.0: Using MSI(-X) interrupts > serial 0000:18:00.0: Setup PCI port: port 40c0, irq 104, type 0 > 0000:18:00.0: ttyS6 at I/O 0x40c0 (irq = 104, base_baud = 115200) is a > XR16850 > serial 0000:18:00.0: Setup PCI port: port 40c8, irq 104, type 0 > 0000:18:00.0: ttyS7 at I/O 0x40c8 (irq = 104, base_baud = 115200) is a > XR16850 > > After loading 8250_pci, lspci -vvs 18:0.0 tells: > > Capabilities: [68] MSI: Enable+ Count=1/32 Maskable+ 64bit+ > Address: 00000000fee000b8 Data: 0000 > Masking: ffffffff Pending: 00000000 > > Looks good so far. Now let's echo to the device. > > $ echo asdf > /dev/ttyS6 > > -- stuck. The echoing process stucks at close(): > > write(1, "asdf\n", 5) = 5 > close(1 > > Stuck in the sense of: the echo is still killable, no crashes. The same > happens if I try to access the device with stty. So something is odd > here. However, the Netmos cards that I whitelisted do a great job. Can you share somehow the `lspci -vvv -xx -nk; lspci -t` with and without MSI enabled? (I want to understand what is going on with it) > So I can't tell if I was just unlucky to grab a card that has issues > with MSI, and this is an exception rather than the rule… -- With Best Regards, Andy Shevchenko
