linux-kernel - Re: [PATCH 1/3] mtd: rawnand: qcom: Add support for status pipe

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Date:   Tue, 28 Sep 2021 21:22:05 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Md Sadre Alam <mdalam@...eaurora.org>
Cc:     miquel.raynal@...tlin.com, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, sricharan@...eaurora.org
Subject: Re: [PATCH 1/3] mtd: rawnand: qcom: Add support for status pipe

On Wed, Sep 15, 2021 at 03:27:29PM +0530, Md Sadre Alam wrote:
> From QPIC V2.0 onwards there is a separate pipe
> to read status of each code word, called "status" pipe.
> 
> "status" pipe will use to read CW status in case of
> enhanced read mode like page scope read, multi page read.
> 

The pipe you are referring to is a DMA pipe (channel). So it should be mentioned
here.

> Signed-off-by: Md Sadre Alam <mdalam@...eaurora.org>
> ---
>  drivers/mtd/nand/raw/qcom_nandc.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
> index 04e6f7b..42c6291 100644
> --- a/drivers/mtd/nand/raw/qcom_nandc.c
> +++ b/drivers/mtd/nand/raw/qcom_nandc.c
> @@ -389,6 +389,7 @@ struct qcom_nand_controller {
>  			struct dma_chan *tx_chan;
>  			struct dma_chan *rx_chan;
>  			struct dma_chan *cmd_chan;
> +			struct dma_chan *sts_chan;
>  		};
>  
>  		/* will be used only by EBI2 for ADM DMA */
> @@ -2737,6 +2738,11 @@ static void qcom_nandc_unalloc(struct qcom_nand_controller *nandc)
>  
>  		if (nandc->cmd_chan)
>  			dma_release_channel(nandc->cmd_chan);
> +
> +		if (nandc->props->qpic_v2) {
> +			if (nandc->sts_chan)
> +				dma_release_channel(nandc->sts_chan);
> +		}
>  	} else {
>  		if (nandc->chan)
>  			dma_release_channel(nandc->chan);
> @@ -2815,6 +2821,14 @@ static int qcom_nandc_alloc(struct qcom_nand_controller *nandc)
>  			goto unalloc;
>  		}
>  
> +		if (nandc->props->qpic_v2) {
> +			nandc->sts_chan = dma_request_slave_channel(nandc->dev, "sts");
> +			if (!nandc->sts_chan) {
> +				dev_err(nandc->dev, "failed to request sts channel\n");
> +				return -ENODEV;
> +			}

If you are forcing the need of status pipe, then you should also update the
devicetree of relevant SoCs using the QPIC v2 controller. Else, they will fail
to probe.

Thanks,
Mani

> +		}
> +
>  		/*
>  		 * Initially allocate BAM transaction to read ONFI param page.
>  		 * After detecting all the devices, this BAM transaction will
> -- 
> 2.7.4
>