Re: [PATCH v2 2/5] firmware: add support for ARM System Control and Power Interface(SCPI) protocol

[Sudeep Holla]

On 20/05/15 12:17, Jon Medhurst (Tixy) wrote:
> On Thu, 2015-05-14 at 16:42 +0100, Sudeep Holla wrote:
> > This patch adds support for System Control and Power Interface (SCPI)
> > Message Protocol used between the Application Cores(AP) and the System
> > Control Processor(SCP). The MHU peripheral provides a mechanism for
> > inter-processor communication between SCP's M3 processor and AP.
> >
> > SCP offers control and management of the core/cluster power states,
> > various power domain DVFS including the core/cluster, certain system
> > clocks configuration, thermal sensors and many others.
> >
> > This protocol driver provides interface for all the client drivers using
> > SCPI to make use of the features offered by the SCP.
> >
> > Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
> > CC: Jassi Brar <jassisinghbrar@xxxxxxxxx>
> > Cc: Liviu Dudau <Liviu.Dudau@xxxxxxx>
> > Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> > Cc: Jon Medhurst (Tixy) <tixy@xxxxxxxxxx>
> > ---
>
> Sorry for the delay in looking at this. I have one nitpick below but
> anyway, here's a
>
> Reviewed-by: Jon Medhurst (Tixy) <tixy@xxxxxxxxxx>

Thanks!

> [...]
> > +++ b/drivers/firmware/arm_scpi.c
> [...]
> > +static void scpi_process_cmd(struct scpi_chan *ch, u32 cmd)
> > +{
> > +	unsigned long flags;
> > +	struct scpi_xfer *t, *match = NULL;
> > +
> > +	spin_lock_irqsave(&ch->rx_lock, flags);
> > +	if (list_empty(&ch->rx_pending)) {
> > +		spin_unlock_irqrestore(&ch->rx_lock, flags);
> > +		return;
> > +	}
> > +
> > +	list_for_each_entry(t, &ch->rx_pending, node)
> > +		if (CMD_XTRACT_UNIQ(t->cmd) == CMD_XTRACT_UNIQ(cmd)) {
> > +			list_del(&t->node);
> > +			match = t;
> > +			break;
> > +		}
> > +	/* check if wait_for_completion is in progress or timed-out */
> > +	if (match && !completion_done(&match->done)) {
> > +		struct scpi_shared_mem *mem = ch->rx_payload;
> > +		int len = min(match->rx_len, CMD_SIZE(cmd));
> > +
> > +		match->status = le32_to_cpu(mem->status);
> > +		memcpy_fromio(match->rx_buf, mem->payload, len);
> > +		if (match->rx_len > len)
>
> rx_len is unsigned and len is signed and so I had to go refresh my
> memory from the C standard before I could convince myself that this if
> statement was OK. Might be clearer if len was unsigned, especially as
> it's the 'min' of two unsigned values.

Fixed locally for next version.

Regards,
Sudeep
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