Re: [PATCH 5/8 v4] dma: k3dma: Add support for dma-channel-mask

Manivannan Sadhasivam
2019-01-17T17:14:41Z

On Wed, Jan 16, 2019 at 09:10:26AM -0800, John Stultz wrote:
> From: Li Yu <liyu65@hisilicon.com>
>
> Add dma-channel-mask as a property for k3dma, it defines
> available dma channels which a non-secure mode driver can use.
>
> One sample usage of this is in Hi3660 SoC. DMA channel 0 is
> reserved to lpm3, which is a coprocessor for power management. So
> as a result, any request in kernel (which runs on main processor
> and in non-secure mode) should start from at least channel 1.
>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Vinod Koul <vkoul@kernel.org>
> Cc: Tanglei Han <hantanglei@huawei.com>
> Cc: Zhuangluan Su <suzhuangluan@hisilicon.com>
> Cc: Ryan Grachek <ryan@edited.us>
> Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> Cc: Guodong Xu <guodong.xu@linaro.org>
> Cc: dmaengine@vger.kernel.org
> Signed-off-by: Li Yu <liyu65@hisilicon.com>
> [jstultz: Reworked to use a channel mask]
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
> v3: Rename to hisi-dma-avail-chan
> v4: Rename to dma-channel-mask
> ---
> drivers/dma/k3dma.c | 20 +++++++++++++++++++-
> 1 file changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/k3dma.c b/drivers/dma/k3dma.c
> index b2060bf..ed19b1f 100644
> --- a/drivers/dma/k3dma.c
> +++ b/drivers/dma/k3dma.c
> @@ -111,6 +111,7 @@ struct k3_dma_dev {
> struct dma_pool *pool;
> u32 dma_channels;
> u32 dma_requests;
> + u32 dma_channel_mask;
> unsigned int irq;
> };
>
> @@ -318,6 +319,9 @@ static void k3_dma_tasklet(unsigned long arg)
> /* check new channel request in d->chan_pending */
> spin_lock_irq(&d->lock);
> for (pch = 0; pch < d->dma_channels; pch++) {
> + if (!(d->dma_channel_mask & (1<<pch)))
> + continue;
> +

As per my comment in bindings patch, the code here gets the assumption
that we are skipping the channels which are not masked. Either the
property should be named as "dma-avail-chan" or "dma_channel_mask" should
have the bit mask of channels which needs to be masked. Then the code will
be,

/* Skip the channels which are masked */
if ((d->dma_channel_mask) & BIT(pch))
continue;

PS: Use BIT() macro where applicable.

Thanks,
Mani

> p = &d->phy[pch];
>
> if (p->vchan == NULL && !list_empty(&d->chan_pending)) {
> @@ -335,6 +339,9 @@ static void k3_dma_tasklet(unsigned long arg)
> spin_unlock_irq(&d->lock);
>
> for (pch = 0; pch < d->dma_channels; pch++) {
> + if (!(d->dma_channel_mask & (1<<pch)))
> + continue;
> +
> if (pch_alloc & (1 << pch)) {
> p = &d->phy[pch];
> c = p->vchan;
> @@ -855,6 +862,13 @@ static int k3_dma_probe(struct platform_device *op)
> "dma-channels", &d->dma_channels);
> of_property_read_u32((&op->dev)->of_node,
> "dma-requests", &d->dma_requests);
> + ret = of_property_read_u32((&op->dev)->of_node,
> + "dma-channel-mask", &d->dma_channel_mask);
> + if (ret) {
> + dev_warn(&op->dev,
> + "dma-channel-mask doesn't exist, considering all as available.\n");
> + d->dma_channel_mask = (u32)~0UL;
> + }
> }
>
> if (!(soc_data->flags & K3_FLAG_NOCLK)) {
> @@ -886,8 +900,12 @@ static int k3_dma_probe(struct platform_device *op)
> return -ENOMEM;
>
> for (i = 0; i < d->dma_channels; i++) {
> - struct k3_dma_phy *p = &d->phy[i];
> + struct k3_dma_phy *p;
> +
> + if (!(d->dma_channel_mask & (1<<i)))
> + continue;
>
> + p = &d->phy[i];
> p->idx = i;
> p->base = d->base + i * 0x40;
> }
> --
> 2.7.4
>