linux-kernel - Re: [PATCH v1 2/2] dmaengine: dw-edma: Add change to remove watermark interrupt enablement

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Message-ID: <20240717083458.GC2574@thinkpad>
Date: Wed, 17 Jul 2024 14:04:58 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Mrinmay Sarkar <quic_msarkar@...cinc.com>
Cc: fancer.lancer@...il.com, vkoul@...nel.org, quic_shazhuss@...cinc.com,
	quic_nitegupt@...cinc.com, quic_ramkri@...cinc.com,
	quic_nayiluri@...cinc.com, quic_krichai@...cinc.com,
	quic_vbadigan@...cinc.com, dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/2] dmaengine: dw-edma: Add change to remove
 watermark interrupt enablement

On Fri, Jul 05, 2024 at 07:25:33PM +0530, Mrinmay Sarkar wrote:

Subject should be:

dmaengine: dw-edma: Do not enable watermark interrupts for HDMA

> DW_HDMA_V0_LIE and DW_HDMA_V0_RIE are initialized as BIT(3) and BIT(4)
> respectively in dw_hdma_control enum. But as per HDMA register these
> bits are corresponds to LWIE and RWIE bit i.e local watermark interrupt
> enable and remote watermarek interrupt enable. In linked list mode LWIE
> and RWIE bits only enable the local and remote watermark interrupt.
> 

I guess you should also rename DW_HDMA_V0_LIE -> DW_HDMA_V0_LWIE and
DW_HDMA_V0_RIE -> DW_HDMA_V0_RWIE in the code, unless the register name changes
with mode.

> As we are not handling watermark interruprt so removing watermark
> interrupt enablement logic to avoid unnecessary watermark interrupt
> event.
> 

How about,

"Since the watermark interrupts are not used but enabled, this leads to
spurious interrupts getting generated. So remove the code that enables them
to avoid generating spurious watermark interrupts."

> Signed-off-by: Mrinmay Sarkar <quic_msarkar@...cinc.com>

Again, please include Fixes tag and CC stable.

> ---
>  drivers/dma/dw-edma/dw-hdma-v0-core.c | 12 +-----------
>  1 file changed, 1 insertion(+), 11 deletions(-)
> 
> diff --git a/drivers/dma/dw-edma/dw-hdma-v0-core.c b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> index 88bd652f..aaf2e27 100644
> --- a/drivers/dma/dw-edma/dw-hdma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-hdma-v0-core.c
> @@ -197,23 +197,13 @@ static void dw_hdma_v0_core_write_chunk(struct dw_edma_chunk *chunk)
>  	struct dw_edma_burst *child;
>  	struct dw_edma_chan *chan = chunk->chan;

This becomes unused as reported by bot.

- Mani

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