Re: [PATCH 3/7] soc: qcom: geni: Add support for gpi dma

Bjorn Andersson
2021-01-11T15:41:58Z

On Mon 11 Jan 09:16 CST 2021, Vinod Koul wrote:

> GPI DMA is one of the DMA modes supported on geni, this adds support to
> enable that mode
>
> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> ---
> drivers/soc/qcom/qcom-geni-se.c | 39 ++++++++++++++++++++++++++++++++-
> include/linux/qcom-geni-se.h | 4 ++++
> 2 files changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c
> index a3868228ea05..db44dc32e049 100644
> --- a/drivers/soc/qcom/qcom-geni-se.c
> +++ b/drivers/soc/qcom/qcom-geni-se.c
> @@ -310,6 +310,39 @@ static void geni_se_select_dma_mode(struct geni_se *se)
> writel_relaxed(val, se->base + SE_GENI_DMA_MODE_EN);
> }
>
> +static int geni_se_select_gpi_mode(struct geni_se *se)

This doesn't return any information and the return value isn't looked
at, please make it void.

> +{
> + unsigned int geni_dma_mode = 0;
> + unsigned int gpi_event_en = 0;
> + unsigned int common_geni_m_irq_en = 0;
> + unsigned int common_geni_s_irq_en = 0;

These could certainly be given a shorter name.

None of them needs to be initialized, first access in all cases are
assignments.

> +
> + common_geni_m_irq_en = readl_relaxed(se->base + SE_GENI_M_IRQ_EN);
> + common_geni_s_irq_en = readl_relaxed(se->base + SE_GENI_S_IRQ_EN);
> + common_geni_m_irq_en &=
> + ~(M_CMD_DONE_EN | M_TX_FIFO_WATERMARK_EN |
> + M_RX_FIFO_WATERMARK_EN | M_RX_FIFO_LAST_EN);
> + common_geni_s_irq_en &= ~S_CMD_DONE_EN;
> + geni_dma_mode = readl_relaxed(se->base + SE_GENI_DMA_MODE_EN);
> + gpi_event_en = readl_relaxed(se->base + SE_GSI_EVENT_EN);
> +
> + geni_dma_mode |= GENI_DMA_MODE_EN;
> + gpi_event_en |= (DMA_RX_EVENT_EN | DMA_TX_EVENT_EN |
> + GENI_M_EVENT_EN | GENI_S_EVENT_EN);

Please reorder these so that you do
readl(m)
mask out bits of m

readl(s)
mask out bits of s

...

> +
> + writel_relaxed(0, se->base + SE_IRQ_EN);
> + writel_relaxed(common_geni_s_irq_en, se->base + SE_GENI_S_IRQ_EN);
> + writel_relaxed(common_geni_m_irq_en, se->base + SE_GENI_M_IRQ_EN);
> + writel_relaxed(0xFFFFFFFF, se->base + SE_GENI_M_IRQ_CLEAR);

Lowercase hex digits please.

> + writel_relaxed(0xFFFFFFFF, se->base + SE_GENI_S_IRQ_CLEAR);
> + writel_relaxed(0xFFFFFFFF, se->base + SE_DMA_TX_IRQ_CLR);
> + writel_relaxed(0xFFFFFFFF, se->base + SE_DMA_RX_IRQ_CLR);
> + writel_relaxed(geni_dma_mode, se->base + SE_GENI_DMA_MODE_EN);
> + writel_relaxed(gpi_event_en, se->base + SE_GSI_EVENT_EN);

Why is this driver using _relaxed accessors exclusively? Why are you
using _relaxed versions?

And wouldn't it be suitable to have a wmb() before the "dma mode enable"
and "event enable" at least? (I.e. use writel() instead)

Regards,
Bjorn

> +
> + return 0;
> +}
> +
> /**
> * geni_se_select_mode() - Select the serial engine transfer mode
> * @se: Pointer to the concerned serial engine.
> @@ -317,7 +350,8 @@ static void geni_se_select_dma_mode(struct geni_se *se)
> */
> void geni_se_select_mode(struct geni_se *se, enum geni_se_xfer_mode mode)
> {
> - WARN_ON(mode != GENI_SE_FIFO && mode != GENI_SE_DMA);
> + WARN_ON(mode != GENI_SE_FIFO && mode != GENI_SE_DMA &&
> + mode != GENI_GPI_DMA);
>
> switch (mode) {
> case GENI_SE_FIFO:
> @@ -326,6 +360,9 @@ void geni_se_select_mode(struct geni_se *se, enum geni_se_xfer_mode mode)
> case GENI_SE_DMA:
> geni_se_select_dma_mode(se);
> break;
> + case GENI_GPI_DMA:
> + geni_se_select_gpi_mode(se);
> + break;
> case GENI_SE_INVALID:
> default:
> break;
> diff --git a/include/linux/qcom-geni-se.h b/include/linux/qcom-geni-se.h
> index cb4e40908f9f..12003a6cb133 100644
> --- a/include/linux/qcom-geni-se.h
> +++ b/include/linux/qcom-geni-se.h
> @@ -12,6 +12,7 @@
> enum geni_se_xfer_mode {
> GENI_SE_INVALID,
> GENI_SE_FIFO,
> + GENI_GPI_DMA,
> GENI_SE_DMA,
> };
>
> @@ -123,6 +124,9 @@ struct geni_se {
> #define CLK_DIV_MSK GENMASK(15, 4)
> #define CLK_DIV_SHFT 4
>
> +/* GENI_IF_DISABLE_RO fields */
> +#define FIFO_IF_DISABLE (BIT(0))
> +
> /* GENI_FW_REVISION_RO fields */
> #define FW_REV_PROTOCOL_MSK GENMASK(15, 8)
> #define FW_REV_PROTOCOL_SHFT 8
> --
> 2.26.2
>