On 08/06/17 12:06, Arnd Bergmann wrote:

On Thu, Jun 8, 2017 at 11:39 AM, Sudeep Holla [off-list ref] wrote:

quoted

On 07/06/17 21:38, Arnd Bergmann wrote:

quoted

On Wed, Jun 7, 2017 at 6:10 PM, Sudeep Holla [off-list ref] wrote:

quoted

+struct scmi_msg_resp_power_attributes {
+       __le16 num_domains;
+       __le16 reserved;
+       __le32 stats_addr_low;
+       __le32 stats_addr_high;
+       __le32 stats_size;
+} __packed;
+
+struct scmi_msg_resp_power_domain_attributes {
+       __le32 flags;
+#define SUPPORTS_STATE_SET_NOTIFY(x)   ((x) & BIT(31))
+#define SUPPORTS_STATE_SET_ASYNC(x)    ((x) & BIT(30))
+#define SUPPORTS_STATE_SET_SYNC(x)     ((x) & BIT(29))
+           u8 name[SCMI_MAX_STR_SIZE];
+} __packed;

I think it would be better to leave out the __packed here, which
can lead to rather inefficient code. It's only really a problem when
building with -mstrict-align, but it's better to write code in a way that
doesn't rely on that.

I assume you are referring to above structure only and not general
across all the structures ? I will have a look at this one.

I meant all of them, from my first look they all seem to have natural
alignment on all members anyway. If there is one that doesn't, I would
suggest annotating the individual unaligned members with __packed.

OK, I will take a deeper look. Thanks for the suggestion.

quoted

quoted

quoted

+static int
+scmi_power_domain_attributes_get(struct scmi_handle *handle, u32 domain,
+                                struct power_dom_info *dom_info)
+{
+       int ret;
+       struct scmi_xfer *t;
+       struct scmi_msg_resp_power_domain_attributes *attr;
+
+       ret = scmi_one_xfer_init(handle, POWER_DOMAIN_ATTRIBUTES,
+                                SCMI_PROTOCOL_POWER, sizeof(domain),
+                                sizeof(*attr), &t);
+       if (ret)
+               return ret;
+
+       *(__le32 *)t->tx.buf = cpu_to_le32(domain);
+       attr = (struct scmi_msg_resp_power_domain_attributes *)t->rx.buf;

It seems you require a similar pattern in each caller of scmi_one_xfer_init(),
but it seems a little clumsy to always require those casts, so maybe there
is a nicer way to do this. How about making scmi_one_xfer_init() act
as an allocation function and having it return the buffer or a PTR_ERR?

Yes I agree it doesn't looks all nice. I have changed these few times
while developing and then thought it's better to get some suggestions. I
am open to any suggestions that will help to make these nicer.

quoted

It also seems odd to have it named 'init' but actually allocate the scmi_xfer
structure rather than filling a local variable that gets passed by reference.

It does initialise but partially. scmi_one_xfer_get does pure allocation
while scmi_one_xfer_init initialise header variables and also tx/rx
size. But if you think it's odd, I will looks at ways to make it better.

Yes, I'm still thinking about it, but I think we can do better. If a function
has both allocation and initialization parts in it, I would probably name
it *_alloc() rather than *_init().

What is the relation between scmi_one_xfer_get() and
scmi_one_xfer_init()? Do we need both in some callers, or
just one of the two?

Currently only scmi_one_xfer_init is used. Initially I was using
scmi_one_xfer_get and initialising at callsite. Strictly speaking, all
the allocations are done at probe time, it's only grabbing and releasing
one at a time at runtime, hence the name _get and _put. I can merge
_init into _get. The way it-is is just artifact of how it got developed :(
-- 
Regards,
Sudeep
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