linux-kernel - Re: [PATCH v2] dmaengine: ioat: fixing the wrong dma

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Message-ID: <10a54c9e-eac5-b270-c7ba-262d9b920aed@intel.com>
Date:   Tue, 15 Aug 2023 08:46:43 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     Yajun Deng <yajun.deng@...ux.dev>, <vkoul@...nel.org>,
        <dan.j.williams@...el.com>
CC:     <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] dmaengine: ioat: fixing the wrong dma_dev->chancnt



On 8/14/23 23:11, Yajun Deng wrote:
> The chancnt would be updated in __dma_async_device_channel_register(),
> but it was assigned in ioat_enumerate_channels(). Therefore chancnt has
> the wrong value.
> 
> Add chancnt member to the struct ioatdma_device, ioat_dma->chancnt
> is used in ioat, dma_dev->chancnt is used in dmaengine.
> 
> Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>

Thanks!

> ---
> V1 -> V2: add chancnt member to the struct ioatdma_device.
> ---
>   drivers/dma/ioat/dma.h  |  1 +
>   drivers/dma/ioat/init.c | 19 ++++++++++---------
>   2 files changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
> index 35e06b382603..a180171087a8 100644
> --- a/drivers/dma/ioat/dma.h
> +++ b/drivers/dma/ioat/dma.h
> @@ -74,6 +74,7 @@ struct ioatdma_device {
>   	struct dca_provider *dca;
>   	enum ioat_irq_mode irq_mode;
>   	u32 cap;
> +	int chancnt;
>   
>   	/* shadow version for CB3.3 chan reset errata workaround */
>   	u64 msixtba0;
> diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c
> index c4602bfc9c74..9c364e92cb82 100644
> --- a/drivers/dma/ioat/init.c
> +++ b/drivers/dma/ioat/init.c
> @@ -420,7 +420,7 @@ int ioat_dma_setup_interrupts(struct ioatdma_device *ioat_dma)
>   
>   msix:
>   	/* The number of MSI-X vectors should equal the number of channels */
> -	msixcnt = ioat_dma->dma_dev.chancnt;
> +	msixcnt = ioat_dma->chancnt;
>   	for (i = 0; i < msixcnt; i++)
>   		ioat_dma->msix_entries[i].entry = i;
>   
> @@ -511,7 +511,7 @@ static int ioat_probe(struct ioatdma_device *ioat_dma)
>   	dma_cap_set(DMA_MEMCPY, dma->cap_mask);
>   	dma->dev = &pdev->dev;
>   
> -	if (!dma->chancnt) {
> +	if (!ioat_dma->chancnt) {
>   		dev_err(dev, "channel enumeration error\n");
>   		goto err_setup_interrupts;
>   	}
> @@ -567,15 +567,16 @@ static void ioat_enumerate_channels(struct ioatdma_device *ioat_dma)
>   	struct device *dev = &ioat_dma->pdev->dev;
>   	struct dma_device *dma = &ioat_dma->dma_dev;
>   	u8 xfercap_log;
> +	int chancnt;
>   	int i;
>   
>   	INIT_LIST_HEAD(&dma->channels);
> -	dma->chancnt = readb(ioat_dma->reg_base + IOAT_CHANCNT_OFFSET);
> -	dma->chancnt &= 0x1f; /* bits [4:0] valid */
> -	if (dma->chancnt > ARRAY_SIZE(ioat_dma->idx)) {
> +	chancnt = readb(ioat_dma->reg_base + IOAT_CHANCNT_OFFSET);
> +	chancnt &= 0x1f; /* bits [4:0] valid */
> +	if (chancnt > ARRAY_SIZE(ioat_dma->idx)) {
>   		dev_warn(dev, "(%d) exceeds max supported channels (%zu)\n",
> -			 dma->chancnt, ARRAY_SIZE(ioat_dma->idx));
> -		dma->chancnt = ARRAY_SIZE(ioat_dma->idx);
> +			 chancnt, ARRAY_SIZE(ioat_dma->idx));
> +		chancnt = ARRAY_SIZE(ioat_dma->idx);
>   	}
>   	xfercap_log = readb(ioat_dma->reg_base + IOAT_XFERCAP_OFFSET);
>   	xfercap_log &= 0x1f; /* bits [4:0] valid */
> @@ -583,7 +584,7 @@ static void ioat_enumerate_channels(struct ioatdma_device *ioat_dma)
>   		return;
>   	dev_dbg(dev, "%s: xfercap = %d\n", __func__, 1 << xfercap_log);
>   
> -	for (i = 0; i < dma->chancnt; i++) {
> +	for (i = 0; i < chancnt; i++) {
>   		ioat_chan = kzalloc(sizeof(*ioat_chan), GFP_KERNEL);
>   		if (!ioat_chan)
>   			break;
> @@ -596,7 +597,7 @@ static void ioat_enumerate_channels(struct ioatdma_device *ioat_dma)
>   			break;
>   		}
>   	}
> -	dma->chancnt = i;
> +	ioat_dma->chancnt = i;
>   }
>   
>   /**