linux-kernel - Re: [PATCH] dmaengine: idxd: Fix default allowed read buffers value in group

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Message-ID: <a3f1229c-9c1e-03a8-4000-13af0970b0de@intel.com>
Date:   Fri, 27 Jan 2023 12:40:23 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     Fenghua Yu <fenghua.yu@...el.com>, Vinod Koul <vkoul@...nel.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        dmaengine@...r.kernel.org, Ramesh Thomas <ramesh.thomas@...el.com>,
        Nikhil Rao <nikhil.rao@...el.com>
Subject: Re: [PATCH] dmaengine: idxd: Fix default allowed read buffers value
 in group



On 1/27/23 12:28 PM, Fenghua Yu wrote:
> Currently default read buffers that is allowed in a group is 0.
> grpcfg will be configured to max read buffers that IDXD can support if
> the group's allowed read buffers value is 0. But 0 is an invalid
> read buffers value and user may get confused when seeing the invalid
> initial value 0 through sysfs interface.
> 
> To show only valid allowed read buffers value and eliminate confusion,
> directly initialize the allowed read buffers to IDXD's max read buffers.
> User still can change the value through sysfs interface.
> 
> Suggested-by: Ramesh Thomas <ramesh.thomas@...el.com>
> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
> Reviewed-by: Nikhil Rao <nikhil.rao@...el.com>

Reviewed-by: Dave Jiang <dave.jiang@...el.com>

> ---
>   drivers/dma/idxd/device.c | 12 ++++++------
>   drivers/dma/idxd/init.c   |  5 +++++
>   2 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
> index 29dbb0f52e18..8d0e3aab2ad2 100644
> --- a/drivers/dma/idxd/device.c
> +++ b/drivers/dma/idxd/device.c
> @@ -699,7 +699,11 @@ static void idxd_groups_clear_state(struct idxd_device *idxd)
>   		group->num_engines = 0;
>   		group->num_wqs = 0;
>   		group->use_rdbuf_limit = false;
> -		group->rdbufs_allowed = 0;
> +		/*
> +		 * The default value is the same as the value of
> +		 * total read buffers in GRPCAP.
> +		 */
> +		group->rdbufs_allowed = idxd->max_rdbufs;
>   		group->rdbufs_reserved = 0;
>   		if (idxd->hw.version < DEVICE_VERSION_2 && !tc_override) {
>   			group->tc_a = 1;
> @@ -934,11 +938,7 @@ static void idxd_group_flags_setup(struct idxd_device *idxd)
>   			group->grpcfg.flags.tc_b = group->tc_b;
>   		group->grpcfg.flags.use_rdbuf_limit = group->use_rdbuf_limit;
>   		group->grpcfg.flags.rdbufs_reserved = group->rdbufs_reserved;
> -		if (group->rdbufs_allowed)
> -			group->grpcfg.flags.rdbufs_allowed = group->rdbufs_allowed;
> -		else
> -			group->grpcfg.flags.rdbufs_allowed = idxd->max_rdbufs;
> -
> +		group->grpcfg.flags.rdbufs_allowed = group->rdbufs_allowed;
>   		group->grpcfg.flags.desc_progress_limit = group->desc_progress_limit;
>   		group->grpcfg.flags.batch_progress_limit = group->batch_progress_limit;
>   	}
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index 529ea09c9094..b2df604e8a5f 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -302,6 +302,11 @@ static int idxd_setup_groups(struct idxd_device *idxd)
>   			group->tc_a = -1;
>   			group->tc_b = -1;
>   		}
> +		/*
> +		 * The default value is the same as the value of
> +		 * total read buffers in GRPCAP.
> +		 */
> +		group->rdbufs_allowed = idxd->max_rdbufs;
>   	}
>   
>   	return 0;