[PATCH v7 2/7] mailbox: arm_mhu: add driver for ARM MHU controller

On Wed, Mar 18, 2015 at 3:55 PM, Sudeep Holla [off-list ref] wrote:

quoted

+static int mhu_send_data(struct mbox_chan *chan, void *data)
+{
+       struct mhu_link *mlink = chan->con_priv;
+       u32 *arg = data;

Arnd doesn't like this and had suggestions in some other thread.

No, Arnd suggested doing it this way. And another platform's driver
was made to do this way.

quoted

+       writel_relaxed(*arg, mlink->tx_reg + INTR_SET_OFS);
+
+       return 0;
+}
+
+static int mhu_startup(struct mbox_chan *chan)
+{
+       struct mhu_link *mlink = chan->con_priv;
+       u32 val;
+       int ret;
+
+       val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
+       writel_relaxed(val, mlink->tx_reg + INTR_CLR_OFS);
+
+       ret = request_irq(mlink->irq, mhu_rx_interrupt,
+                         IRQF_SHARED, "mhu_link", chan);

Any reason we can't move this to probe and have {en,dis}able_irq here if
needed. I has seen it was too heavy to have these especially when
sending small packets.

I see you used to do memcpy in irq-handler
https://git.linaro.org/landing-teams/working/arm/kernel.git/blob/HEAD:/drivers/mailbox/arm_mhu.c
perhaps you were using your old driver?

If you use this new driver, and send packets so often that
request-release irq has effect, maybe should hold the mailbox
reference for lifetime. I remember suggesting you that already and I
remember you said that's how it was.

-Jassi