[PATCH] tty: serial: 8250: Fixes: Fix port count mismatch with the device

[PATCH] tty: serial: 8250: Fixes: Fix port count mismatch with the device

[Crescent Hsieh]

Normally, the number of ports is indicated by the third digit of the
device ID on Moxa PCI serial boards. For example, `0x1121` indicates a
device with 2 ports.

However, `CP116E_A_A` and `CP116E_A_B` are exceptions; they have 8
ports, but the third digit of the device ID is `6`.

This patch introduces a function to retrieve the number of ports on Moxa
PCI serial boards, addressing the issue described above.

Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
---
 drivers/tty/serial/8250/8250_pci.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 40af74b55933..e1d7aa2fa347 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1985,6 +1985,17 @@ enum {
 	MOXA_SUPP_RS485 = BIT(2),
 };
 
+static unsigned short moxa_get_nports(unsigned short device)
+{
+	switch (device) {
+	case PCI_DEVICE_ID_MOXA_CP116E_A_A:
+	case PCI_DEVICE_ID_MOXA_CP116E_A_B:
+		return 8;
+	}
+
+	return FIELD_GET(0x00F0, device);
+}
+
 static bool pci_moxa_is_mini_pcie(unsigned short device)
 {
 	if (device == PCI_DEVICE_ID_MOXA_CP102N	||
@@ -2038,7 +2049,7 @@ static int pci_moxa_init(struct pci_dev *dev)
 {
 	unsigned short device = dev->device;
 	resource_size_t iobar_addr = pci_resource_start(dev, 2);
-	unsigned int num_ports = (device & 0x00F0) >> 4, i;
+	unsigned int i, num_ports = moxa_get_nports(device);
 	u8 val, init_mode = MOXA_RS232;
 
 	if (!(pci_moxa_supported_rs(dev) & MOXA_SUPP_RS232)) {
-- 
2.34.1

Re: [PATCH] tty: serial: 8250: Fixes: Fix port count mismatch with the device

[Greg Kroah-Hartman]

On Fri, Jun 14, 2024 at 05:03:22PM +0800, Crescent Hsieh wrote:
> Normally, the number of ports is indicated by the third digit of the
> device ID on Moxa PCI serial boards. For example, `0x1121` indicates a
> device with 2 ports.
> 
> However, `CP116E_A_A` and `CP116E_A_B` are exceptions; they have 8
> ports, but the third digit of the device ID is `6`.
> 
> This patch introduces a function to retrieve the number of ports on Moxa
> PCI serial boards, addressing the issue described above.
> 
> Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
> ---
>  drivers/tty/serial/8250/8250_pci.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)

What commit id does this fix?

thanks,

greg k-h

Re: [PATCH] tty: serial: 8250: Fixes: Fix port count mismatch with the device

[Crescent CY Hsieh]

On Fri, Jun 14, 2024 at 11:07:29AM +0200, Greg Kroah-Hartman wrote:
> On Fri, Jun 14, 2024 at 05:03:22PM +0800, Crescent Hsieh wrote:
> > Normally, the number of ports is indicated by the third digit of the
> > device ID on Moxa PCI serial boards. For example, `0x1121` indicates a
> > device with 2 ports.
> > 
> > However, `CP116E_A_A` and `CP116E_A_B` are exceptions; they have 8
> > ports, but the third digit of the device ID is `6`.
> > 
> > This patch introduces a function to retrieve the number of ports on Moxa
> > PCI serial boards, addressing the issue described above.
> > 
> > Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
> > ---
> >  drivers/tty/serial/8250/8250_pci.c | 13 ++++++++++++-
> >  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> What commit id does this fix?

None, it's just a normal patch, I might have mistakenly added the "fix"
tag.

---
Sincerely,
Crescent Hsieh

Re: [PATCH] tty: serial: 8250: Fixes: Fix port count mismatch with the device

[Greg Kroah-Hartman]

On Sat, Jun 15, 2024 at 01:36:52PM +0800, Crescent CY Hsieh wrote:
> On Fri, Jun 14, 2024 at 11:07:29AM +0200, Greg Kroah-Hartman wrote:
> > On Fri, Jun 14, 2024 at 05:03:22PM +0800, Crescent Hsieh wrote:
> > > Normally, the number of ports is indicated by the third digit of the
> > > device ID on Moxa PCI serial boards. For example, `0x1121` indicates a
> > > device with 2 ports.
> > > 
> > > However, `CP116E_A_A` and `CP116E_A_B` are exceptions; they have 8
> > > ports, but the third digit of the device ID is `6`.
> > > 
> > > This patch introduces a function to retrieve the number of ports on Moxa
> > > PCI serial boards, addressing the issue described above.
> > > 
> > > Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
> > > ---
> > >  drivers/tty/serial/8250/8250_pci.c | 13 ++++++++++++-
> > >  1 file changed, 12 insertions(+), 1 deletion(-)
> > 
> > What commit id does this fix?
> 
> None, it's just a normal patch, I might have mistakenly added the "fix"
> tag.

You say "fix" twice in the subject line, and it looks like it actually
does resolve a problem in the current code.

Or is this all just a "cleanup" change?

confused,

greg k-h

Re: [PATCH] tty: serial: 8250: Fixes: Fix port count mismatch with the device

[Crescent CY Hsieh]

On Sat, Jun 15, 2024 at 08:18:41AM +0200, Greg Kroah-Hartman wrote:
> On Sat, Jun 15, 2024 at 01:36:52PM +0800, Crescent CY Hsieh wrote:
> > On Fri, Jun 14, 2024 at 11:07:29AM +0200, Greg Kroah-Hartman wrote:
> > > On Fri, Jun 14, 2024 at 05:03:22PM +0800, Crescent Hsieh wrote:
> > > > Normally, the number of ports is indicated by the third digit of the
> > > > device ID on Moxa PCI serial boards. For example, `0x1121` indicates a
> > > > device with 2 ports.
> > > > 
> > > > However, `CP116E_A_A` and `CP116E_A_B` are exceptions; they have 8
> > > > ports, but the third digit of the device ID is `6`.
> > > > 
> > > > This patch introduces a function to retrieve the number of ports on Moxa
> > > > PCI serial boards, addressing the issue described above.
> > > > 
> > > > Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
> > > > ---
> > > >  drivers/tty/serial/8250/8250_pci.c | 13 ++++++++++++-
> > > >  1 file changed, 12 insertions(+), 1 deletion(-)
> > > 
> > > What commit id does this fix?
> > 
> > None, it's just a normal patch, I might have mistakenly added the "fix"
> > tag.
> 
> You say "fix" twice in the subject line, and it looks like it actually
> does resolve a problem in the current code.
> 
> Or is this all just a "cleanup" change?
> 
> confused,

After reviewing what this patch has done, I found that it does fix the
problem of retrieving the wrong number of ports on some Moxa PCI serial
devices. However, this issue is not severe enough to cause any system
problems.

Sorry for the confusion.

---
Sincerely,
Crescent Hsieh

Re: [PATCH] tty: serial: 8250: Fixes: Fix port count mismatch with the device

[Andy Shevchenko]

On Sun, Jun 16, 2024 at 6:16 AM Crescent CY Hsieh
<crescentcy.hsieh@moxa.com> wrote:
> On Sat, Jun 15, 2024 at 08:18:41AM +0200, Greg Kroah-Hartman wrote:
> > On Sat, Jun 15, 2024 at 01:36:52PM +0800, Crescent CY Hsieh wrote:
> > > On Fri, Jun 14, 2024 at 11:07:29AM +0200, Greg Kroah-Hartman wrote:
> > > > On Fri, Jun 14, 2024 at 05:03:22PM +0800, Crescent Hsieh wrote:

...

> > > > What commit id does this fix?
> > >
> > > None, it's just a normal patch, I might have mistakenly added the "fix"
> > > tag.
> >
> > You say "fix" twice in the subject line, and it looks like it actually
> > does resolve a problem in the current code.
> >
> > Or is this all just a "cleanup" change?
> >
> > confused,
>
> After reviewing what this patch has done, I found that it does fix the
> problem of retrieving the wrong number of ports on some Moxa PCI serial
> devices. However, this issue is not severe enough to cause any system
> problems.

Yes, but it is still a fix. So, which commit does it fix? We may add a
Fixes tag then.


-- 
With Best Regards,
Andy Shevchenko