Re: [patch 07/10] can: c_can: Simplify buffer reenabling

[Oliver Hartkopp <socketcan@hartkopp.net>]

Hello Thomas, hello Alexander,

I just took a short look into the C_CAN manual.

-------- Original Message --------
Subject: [patch 07/10] can: c_can: Simplify buffer reenabling

(..)

Instead of writing to the message object we can simply clear the
NewDat bit with the get method.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 drivers/net/can/c_can/c_can.c |   16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

Index: linux-can/drivers/net/can/c_can/c_can.c
===================================================================
--- linux-can.orig/drivers/net/can/c_can/c_can.c
+++ linux-can/drivers/net/can/c_can/c_can.c

(..)

 /* For the high buffers we clear the interrupt bit and newdat */
-#define IF_COMM_RCV_HIGH	(IF_COMM_RCV_LOW | IF_COMM_TXRQST)
+#define IF_COMM_RCV_HIGH	(IF_COMM_RCV_LOW | IF_COMM_CLR_NEWDAT)


I wonder if it generally works correctly, when the interrupt and newdat bits
are handled separately, as the manual states:

4.8.1 Reading from a FIFO Buffer
When the CPU transfers the contents of Message Object to the IFx Message
Bugger registers by writing its number to the IFx Command Request Register,
the corresponding Command Mask Register should be programmed the way that bits
NewDat and IntPnd are reset to zero
(TxRqst/NewDat = ‘1’ and ClrIntPnd = ‘1’).

The driver seems to write these bits in different steps.

Regards,
Oliver