Re: [PATCH v4 2/2] fsi: Add IBM I2C Responder virtual FSI master

[Steven Rostedt <rostedt@goodmis.org>]

On Thu,  2 Feb 2023 13:19:26 -0600
Eddie James <eajames@linux.ibm.com> wrote:

> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(i2cr_i2c_error,
> +	TP_PROTO(const struct i2c_client *client, __be32 command, int rc),
> +	TP_ARGS(client, command, rc),
> +	TP_STRUCT__entry(
> +		__field(int, bus)
> +		__field(unsigned short, addr)

For all of these, I would put the "unsigned short addr" at the end of
the TP_STRUCT__entry(). That's because you will inject two wasted bytes
in the structure that is generated. Granted, the tracing will likely
word align the result anyway, but still, we don't want holes in the
middle of the structure.

-- Steve


> +		__array(unsigned char, command, sizeof(__be32))
> +		__field(int, rc)
> +	),
> +	TP_fast_assign(
> +		__entry->bus = client->adapter->nr;
> +		__entry->addr = client->addr;
> +		memcpy(__entry->command, &command, sizeof(__be32));
> +		__entry->rc = rc;
> +	),
> +	TP_printk("%d-%02x command:{ %*ph } rc:%d", __entry->bus, __entry->addr,
> +		  (int)sizeof(__be32), __entry->command, __entry->rc)
> +);
> +
> +TRACE_EVENT(i2cr_read,
> +	TP_PROTO(const struct i2c_client *client, uint32_t address, size_t size, __be64 result),
> +	TP_ARGS(client, address, size, result),
> +	TP_STRUCT__entry(
> +		__field(int, bus)
> +		__field(unsigned short, addr)
> +		__field(uint32_t, address)
> +		__field(size_t, size)
> +		__array(unsigned char, result, sizeof(__be64))
> +	),
> +	TP_fast_assign(
> +		__entry->bus = client->adapter->nr;
> +		__entry->addr = client->addr;
> +		__entry->address = address;
> +		__entry->size = size;
> +		memcpy(__entry->result, &result, sizeof(__be64));
> +	),
> +	TP_printk("%d-%02x address:%08x size:%zu { %*ph }", __entry->bus, __entry->addr,
> +		  __entry->address, __entry->size, (int)__entry->size, __entry->result)
> +);
> +