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Subject: Re: [PATCH] dmaengine: hisi_dma: fix MSI allocate fail when reload
 hisi_dma
To:     Jie Hai <haijie1@huawei.com>, <wangzhou1@hisilicon.com>,
        <vkoul@kernel.org>
References: <20220216072101.34473-1-haijie1@huawei.com>
CC:     <dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>
From:   Dongdong Liu <liudongdong3@huawei.com>
Message-ID: <cc687bb8-c1b5-d54a-a563-bd8f3923e7b5@huawei.com>
Date:   Wed, 23 Mar 2022 19:10:04 +0800
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Looks good.

Reviewed-by: Dongdong Liu <liudongdong3@huawei.com>

Thanks,
Dongdong
On 2022/2/16 15:21, Jie Hai wrote:
> Remove the loaded hisi_dma driver and reload it, the driver fails
> to work properly. The following error is reported in the kernel log:
>
> [ 1475.597609] hisi_dma 0000:7b:00.0: Failed to allocate MSI vectors!
> [ 1475.604915] hisi_dma: probe of 0000:7b:00.0 failed with error -28
>
> As noted in "The MSI Driver Guide HOWTO"[1], the number of MSI
> interrupt must be a power of two. The Kunpeng DMA driver allocates 30
> MSI interrupts. As a result, no space left on device is reported
> when the driver is reloaded and allocates interrupt vectors from the
> interrupt domain.
>
> This patch changes the number of interrupt vectors allocated by
> hisi_dma driver to 32 to avoid this problem.
>
> [1] https://www.kernel.org/doc/html/latest/PCI/msi-howto.html
>
> Fixes: e9f08b65250d ("dmaengine: hisilicon: Add Kunpeng DMA engine support")
>
> Signed-off-by: Jie Hai <haijie1@huawei.com>
> ---
>  drivers/dma/hisi_dma.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/dma/hisi_dma.c b/drivers/dma/hisi_dma.c
> index 97c87a7cba87..43817ced3a3e 100644
> --- a/drivers/dma/hisi_dma.c
> +++ b/drivers/dma/hisi_dma.c
> @@ -30,7 +30,7 @@
>  #define HISI_DMA_MODE			0x217c
>  #define HISI_DMA_OFFSET			0x100
>
> -#define HISI_DMA_MSI_NUM		30
> +#define HISI_DMA_MSI_NUM		32
>  #define HISI_DMA_CHAN_NUM		30
>  #define HISI_DMA_Q_DEPTH_VAL		1024
>
>