On Fri, Sep 28, 2018 at 05:40:08PM +0800, Feng Tang wrote: > "pciserial" earlyprintk helps much on many modern x86 platforms, > but unfortunately there are still some platforms whose PCI UART > devices have wrong PCI class code, which will be blocked by current > class code check. > > Add a option "force" so that developer could still use a UART device > even it has wrong class code, with format "",B:D.F,force,baud". And
This new parameter and its meaning needs to be documented where pciserial is documented. > the original format ",B:D.F,baud" is kept unchanged. > > Suggested-by: Borislav Petkov <[email protected]> > Signed-off-by: Feng Tang <[email protected]> > --- > arch/x86/kernel/early_printk.c | 26 ++++++++++++++++++++------ > 1 file changed, 20 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c > index 5e801c8..35d0f66 100644 > --- a/arch/x86/kernel/early_printk.c > +++ b/arch/x86/kernel/early_printk.c > @@ -213,8 +213,10 @@ static unsigned int mem32_serial_in(unsigned long addr, > int offset) > * early_pci_serial_init() > * > * This function is invoked when the early_printk param starts with > "pciserial" > - * The rest of the param should be ",B:D.F,baud" where B, D & F describe the > - * location of a PCI device that must be a UART device. > + * The rest of the param should be ",B:D.F,baud" or ",B:D.F,force,baud", > where > + * B, D & F describe the location of a PCI device that must be a UART device, > + * "force" is optional and means insisting using a UART device with a wrong > + * pci class code. > */ > static __init void early_pci_serial_init(char *s) > { > @@ -224,6 +226,7 @@ static __init void early_pci_serial_init(char *s) > u32 classcode, bar0; > u16 cmdreg; > char *e; > + int force = 0; > > > /* > @@ -252,6 +255,15 @@ static __init void early_pci_serial_init(char *s) > if (*s == ',') > s++; > > + /* User may insist to use a UART device with wrong class code */ > + if (!strncmp(s, "force", 5)) { > + force = 1; > + s += 5; > + > + if (*s == ',') > + s++; No, you need to force the presence of "," otherwise cmdlines like this: earlyprintk=pciserial,0:XX.X,forcedoodoo work too. > + } > + > /* > * Second, find the device from the BDF > */ > @@ -262,10 +274,12 @@ static __init void early_pci_serial_init(char *s) > /* > * Verify it is a UART type device > */ > - if (((classcode >> 16 != PCI_CLASS_COMMUNICATION_MODEM) && > - (classcode >> 16 != PCI_CLASS_COMMUNICATION_SERIAL)) || > - (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */ > - return; > + if (!force) { > + if (((classcode >> 16 != PCI_CLASS_COMMUNICATION_MODEM) && > + (classcode >> 16 != PCI_CLASS_COMMUNICATION_SERIAL)) || > + (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */ > + return; Move the force check in here ^ Thx. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
