Re: [PATCH v2 1/2] usb: xhci-mtk: relax TT periodic bandwidth allocation

[Greg Kroah-Hartman]

On Fri, Aug 05, 2022 at 02:03:27PM +0800, Chunfeng Yun wrote:
> Currently uses the worst case byte budgets on FS/LS bus bandwidth,
> for example, for an isochronos IN endpoint with 192 bytes budget, it
> will consume the whole 5 uframes(188 * 5) while the actual FS bus
> budget should be just 192 bytes. It cause that many usb audio headsets
> with 3 interfaces (audio input, audio output, and HID) cannot be
> configured.
> To improve it, changes to use "approximate" best case budget for FS/LS
> bandwidth management. For the same endpoint from the above example,
> the approximate best case budget is now reduced to (188 * 2) bytes.
> 
> Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
> ---
> v2: change commit message
> ---
>  drivers/usb/host/xhci-mtk-sch.c | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci-mtk-sch.c
>  b/drivers/usb/host/xhci-mtk-sch.c
> index 06a6b19acaae..a17bc584ee99 100644
> --- a/drivers/usb/host/xhci-mtk-sch.c
> +++ b/drivers/usb/host/xhci-mtk-sch.c
> @@ -425,7 +425,6 @@ static int check_fs_bus_bw(struct mu3h_sch_ep_info
>  *sch_ep, int offset)
>  
>  static int check_sch_tt(struct mu3h_sch_ep_info *sch_ep, u32 offset)
>  {
> -	u32 extra_cs_count;
>  	u32 start_ss, last_ss;
>  	u32 start_cs, last_cs;
>  
> @@ -461,18 +460,12 @@ static int check_sch_tt(struct mu3h_sch_ep_info
>  *sch_ep, u32 offset)
>  		if (last_cs > 7)
>  			return -ESCH_CS_OVERFLOW;
>  
> -		if (sch_ep->ep_type == ISOC_IN_EP)
> -			extra_cs_count = (last_cs == 7) ? 1 : 2;
> -		else /*  ep_type : INTR IN / INTR OUT */
> -			extra_cs_count = 1;
> -
> -		cs_count += extra_cs_count;
>  		if (cs_count > 7)
>  			cs_count = 7; /* HW limit */
>  
>  		sch_ep->cs_count = cs_count;
> -		/* one for ss, the other for idle */
> -		sch_ep->num_budget_microframes = cs_count + 2;
> +		/* ss, idle are ignored */
> +		sch_ep->num_budget_microframes = cs_count;
>  
>  		/*
>  		 * if interval=1, maxp >752, num_budge_micoframe is larger
> -- 
> 2.18.0
> 

This doesn't apply to my tree without fuzz, and when I force it, I get a
build error.  Can you please rebase against 6.0-rc1 and resend?

thanks,

greg k-h