Re: [PATCH] can/peak_pci: fix FPGA potential frame loss issue

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 01/20/2016 12:15 PM, Stephane Grosjean wrote:
> This patch installs a workaround when the driver detects one of the
> following PEAK-System CAN interfaces, running a firmware < v1.3.0:

Is the problem fixed on FW >= 1.3.0? Is it possible to update the
firmware? If so, what about printing a warning message about known
problem with the firmware?

> PCAN-PCI Express 1/2/4 CAN; DeviceID 0x0003
> PCAN-PCI/104 Express 1/2/4 CAN; DeviceID 0x0007
> PCAN-miniPCIe 1/2 CAN; DeviceID 0x0008
> PCAN-PCI Express OEM 1/2/4 CAN; DeviceID 0x0009
> PCAN-ExpressCard 34 1 CAN; DeviceID 0x000A
> 
> This fixes potential loss of one tx frame in Linux SMP when some other
> task does another Command Register write (e.g. Release Receive Buffer)
> in between the triggering Tx Request and the next Sample Point.
> 
> This workaround is useless thus *NOT* installed when the firmware
> has been upgraded to v1.3.0 or higher, nor if the CAN interface is equipped
> with true SJA1000 controller(s).
> 
> Signed-off-by: Stephane Grosjean <s.grosjean@peak-system.com>
> ---
>  drivers/net/can/sja1000/peak_pci.c | 34 +++++++++++++++++++++++++++++++++-
>  1 file changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/can/sja1000/peak_pci.c b/drivers/net/can/sja1000/peak_pci.c
> index 131026f..84f7d3a 100644
> --- a/drivers/net/can/sja1000/peak_pci.c
> +++ b/drivers/net/can/sja1000/peak_pci.c
> @@ -30,6 +30,15 @@
>  
>  #include "sja1000.h"
>  
> +#define VERSION_REG1		0x40
> +#define VERSION_REG2		0x44
> +
> +#define VERSION_REG2_MASK	0xfff0

Nitpick:
Please add PCAN_ prefixes to the defines.

> +#define PCAN_PCI_FW(x, y, z)	((((u16 )(x) & 0xf) << 12) | \
> +				 (((u16 )(y) & 0xf) << 8)  | \
> +				 ((      (z) & 0xf) << 4))
> +#define PCAN_PCI_FW_VER(v)	((v) & VERSION_REG2_MASK)
> +
>  MODULE_AUTHOR("Stephane Grosjean <s.grosjean@peak-system.com>");
>  MODULE_DESCRIPTION("Socket-CAN driver for PEAK PCAN PCI family cards");
>  MODULE_SUPPORTED_DEVICE("PEAK PCAN PCI/PCIe/PCIeC miniPCI CAN cards");
> @@ -540,6 +549,19 @@ static void peak_pci_write_reg(const struct sja1000_priv *priv,
>  	writeb(val, priv->reg_base + (port << 2));
>  }

Marc

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