Re: [PATCH v3 1/3] iommu/arm-smmu-v3: Factor out CMDQ batch force-sync conditions

[Will Deacon]

On Mon, Jun 01, 2026 at 10:48:43AM +0000, Ashish Mhetre wrote:
> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> 
> arm_smmu_cmdq_batch_add_cmd_p() carries two distinct reasons for
> flushing the current batch with a CMD_SYNC before appending the
> new command:
> 
>   - The batch's pre-assigned cmdq does not support the new command.
>   - The Arm erratum 2812531 workaround (ARM_SMMU_OPT_CMDQ_FORCE_SYNC)
>     forces a SYNC at one entry before the batch is full.
> 
> Lift those checks into a new arm_smmu_cmdq_batch_force_sync() helper
> so that adding another force-sync condition becomes a one-line
> addition. No functional change.
> 
> Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Signed-off-by: Ashish Mhetre <amhetre@xxxxxxxxxx>
> ---
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 26 ++++++++++++++++-----
>  1 file changed, 20 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> index 9be589d14a3b..4d29bd343460 100644
> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> @@ -847,16 +847,30 @@ static void arm_smmu_cmdq_batch_init_cmd(struct arm_smmu_device *smmu,
>  	cmds->cmdq = arm_smmu_get_cmdq(smmu, cmd);
>  }
>  
> +static bool arm_smmu_cmdq_batch_force_sync(struct arm_smmu_device *smmu,
> +					   struct arm_smmu_cmdq_batch *cmds,
> +					   struct arm_smmu_cmd *cmd)
> +{
> +	if (!cmds->num)
> +		return false;

This check seems new?

Will