diff mbox series

[net-next] ptp: ocp: add UPF_NO_THRE_TEST flag for serial ports

Message ID 20220309223427.34745-1-jonathan.lemon@gmail.com (mailing list archive)
State Accepted
Commit c17c4059df2471183a0e0d567677cbd7f0e0a980
Delegated to: Netdev Maintainers
Headers show
Series [net-next] ptp: ocp: add UPF_NO_THRE_TEST flag for serial ports | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Single patches do not need cover letters
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers success CCed 3 of 3 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/checkpatch warning WARNING: From:/Signed-off-by: email address mismatch: 'From: Jonathan Lemon <bsd@fb.com>' != 'Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>'
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Jonathan Lemon March 9, 2022, 10:34 p.m. UTC 
From: Jonathan Lemon <bsd@fb.com>

The serial port driver attempts to test for correct THRE behavior
on startup.  However, it does this by disabling interrupts, and
then intentionally trying to trigger an interrupt in order to see
if the IIR bit is set in the UART.

However, in this FPGA design, the UART interrupt is generated
through the MSI vector, so when interrupts are re-enabled after
the test, the DMAR-IR reports an unhandled IRTE entry, since
no irq handler is installed at this point - it is installed
after the test.

This only happens on the /second/ open of the UART, since on the
first open, the x86_vector has installed and activated by the
driver probe, and is correctly handled.  When the serial port is
closed for the first time, this vector is deactivated and removed,
leading to this error.

Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
---
 drivers/ptp/ptp_ocp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

patchwork-bot+netdevbpf@kernel.org March 11, 2022, 4:40 a.m. UTC | #1 
Hello:

This patch was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Wed,  9 Mar 2022 14:34:27 -0800 you wrote:
> From: Jonathan Lemon <bsd@fb.com>
> 
> The serial port driver attempts to test for correct THRE behavior
> on startup.  However, it does this by disabling interrupts, and
> then intentionally trying to trigger an interrupt in order to see
> if the IIR bit is set in the UART.
> 
> [...]

Here is the summary with links:
  - [net-next] ptp: ocp: add UPF_NO_THRE_TEST flag for serial ports
    https://git.kernel.org/netdev/net-next/c/c17c4059df24

You are awesome, thank you!
diff mbox series

Patch

diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
index 36c09269a12d..64cc92c2426b 100644
--- a/drivers/ptp/ptp_ocp.c
+++ b/drivers/ptp/ptp_ocp.c
@@ -1752,7 +1752,7 @@  ptp_ocp_serial_line(struct ptp_ocp *bp, struct ocp_resource *r)
 	uart.port.mapbase = pci_resource_start(pdev, 0) + r->offset;
 	uart.port.irq = pci_irq_vector(pdev, r->irq_vec);
 	uart.port.uartclk = 50000000;
-	uart.port.flags = UPF_FIXED_TYPE | UPF_IOREMAP;
+	uart.port.flags = UPF_FIXED_TYPE | UPF_IOREMAP | UPF_NO_THRE_TEST;
 	uart.port.type = PORT_16550A;
 
 	return serial8250_register_8250_port(&uart);