linux-kernel - Re: [PATCH v3 02/14] soc: ti: k3: add navss ringacc driver

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Date:   Tue, 29 Oct 2019 14:22:14 +0530
From:   Lokesh Vutla <lokeshvutla@...com>
To:     Peter Ujfalusi <peter.ujfalusi@...com>, <vkoul@...nel.org>,
        <robh+dt@...nel.org>, <nm@...com>, <ssantosh@...nel.org>
CC:     <dan.j.williams@...el.com>, <dmaengine@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <grygorii.strashko@...com>, <t-kristo@...com>, <tony@...mide.com>,
        <j-keerthy@...com>
Subject: Re: [PATCH v3 02/14] soc: ti: k3: add navss ringacc driver

Hi Grygorii,

[...snip..]

> +
> +static int k3_ringacc_ring_access_io(struct k3_ring *ring, void *elem,
> +				     enum k3_ringacc_access_mode access_mode)
> +{
> +	void __iomem *ptr;
> +
> +	switch (access_mode) {
> +	case K3_RINGACC_ACCESS_MODE_PUSH_HEAD:
> +	case K3_RINGACC_ACCESS_MODE_POP_HEAD:
> +		ptr = (void __iomem *)&ring->fifos->head_data;
> +		break;
> +	case K3_RINGACC_ACCESS_MODE_PUSH_TAIL:
> +	case K3_RINGACC_ACCESS_MODE_POP_TAIL:
> +		ptr = (void __iomem *)&ring->fifos->tail_data;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	ptr += k3_ringacc_ring_get_fifo_pos(ring);
> +
> +	switch (access_mode) {
> +	case K3_RINGACC_ACCESS_MODE_POP_HEAD:
> +	case K3_RINGACC_ACCESS_MODE_POP_TAIL:
> +		dev_dbg(ring->parent->dev,
> +			"memcpy_fromio(x): --> ptr(%p), mode:%d\n", ptr,
> +			access_mode);
> +		memcpy_fromio(elem, ptr, (4 << ring->elm_size));

Does this work for any elem_size < 64 or any element size not aligned with 64?

IIUC, in message mode, ring element should be inserted in a single burst write
and there is no doorbell facility. If the above conditions are not met, we are
supposed to use proxy.

In this driver, I don't see any restrictions on the ring element size for
message mode and directly written to io. Am I missing something?

Thanks and regards,
Lokesh

> +		ring->occ--;
> +		break;
> +	case K3_RINGACC_ACCESS_MODE_PUSH_TAIL:
> +	case K3_RINGACC_ACCESS_MODE_PUSH_HEAD:
> +		dev_dbg(ring->parent->dev,
> +			"memcpy_toio(x): --> ptr(%p), mode:%d\n", ptr,
> +			access_mode);
> +		memcpy_toio(ptr, elem, (4 << ring->elm_size));
> +		ring->free--;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	dev_dbg(ring->parent->dev, "free%d index%d occ%d index%d\n", ring->free,
> +		ring->windex, ring->occ, ring->rindex);
> +	return 0;
> +}
> +
> +static int k3_ringacc_ring_push_head_io(struct k3_ring *ring, void *elem)
> +{
> +	return k3_ringacc_ring_access_io(ring, elem,
> +					 K3_RINGACC_ACCESS_MODE_PUSH_HEAD);
> +}
> +
> +static int k3_ringacc_ring_push_io(struct k3_ring *ring, void *elem)
> +{
> +	return k3_ringacc_ring_access_io(ring, elem,
> +					 K3_RINGACC_ACCESS_MODE_PUSH_TAIL);
> +}
> +
> +static int k3_ringacc_ring_pop_io(struct k3_ring *ring, void *elem)
> +{
> +	return k3_ringacc_ring_access_io(ring, elem,
> +					 K3_RINGACC_ACCESS_MODE_POP_HEAD);
> +}
> +
> +static int k3_ringacc_ring_pop_tail_io(struct k3_ring *ring, void *elem)
> +{
> +	return k3_ringacc_ring_access_io(ring, elem,
> +					 K3_RINGACC_ACCESS_MODE_POP_HEAD);
> +}
> +