Message-ID: <ab09d5de-84bb-41c9-ae74-e62dd5d02d15@quicinc.com>
Date: Tue, 1 Oct 2024 14:44:46 +0530
From: AKASH KUMAR <quic_akakum@...cinc.com>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi
	<balbi@...nel.org>, Jack Pham <quic_jackp@...cinc.com>,
        "kernel@...cinc.com"
	<kernel@...cinc.com>,
        Wesley Cheng <quic_wcheng@...cinc.com>,
        "Laurent
 Pinchart" <laurent.pinchart@...asonboard.com>,
        Daniel Scally
	<dan.scally@...asonboard.com>,
        Vijayavardhan Vennapusa
	<quic_vvreddy@...cinc.com>,
        Krishna Kurapati <quic_kriskura@...cinc.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5] usb: dwc3: gadget: Refine the logic for resizing Tx
 FIFOs

Hi,

On 10/1/2024 6:50 AM, Thinh Nguyen wrote:
> On Sat, Sep 28, 2024, Akash Kumar wrote:
>> The current logic is rigid, setting num_fifos to fixed values.
>> 3 for any maxburst greater than 1.
>> tx_fifo_resize_max_num for maxburst greater than 6.
>> Additionally, it did not differentiate much between bulk and
>> isochronous transfers, applying similar logic to both.
>>
>> The updated logic is more flexible and specifically designed to meet
>> the unique requirements of both bulk and isochronous transfers. We
>> have made every effort to satisfy all needs and requirements,
>> verified on our specific platform and application.
>>
>> The updated logic is more flexible and specifically designed to meet
>> the unique requirements of both bulk and isochronous transfers. We
>> have made every effort to satisfy all needs and requirements, verified
>> on our specific platform and application.
> Was there a copy-and-paste issue with the above paragraph?
yeah my mistake, will fix.
>> Bulk Transfers: Ensures that num_fifos is optimized by considering both
>> the maxburst and DT property tx_fifo_resize_max_num for super speed and
>> above. For high-speed and below bulk endpoints, a 2K TxFIFO allocation
>> is used to meet efficient data transfer needs, considering
>> FIFO-constrained platforms.
>>
>> Isochronous Transfers: Ensures that num_fifos is sufficient by considering
>> the maximum packet multiplier for HS and maxburst for SS, along with a
>> constraint with the DT property tx_fifo_resize_max_num.
>>
>> This change aims to optimize the allocation of Tx FIFOs for both bulk
>> and isochronous endpoints, potentially improving data transfer efficiency
>> and overall performance. It also enhances support for all use cases,
>> which can be tweaked with DT parameters and the endpoint’s maxburst and
>> maxpacket.
>>
>> Signed-off-by: Akash Kumar <quic_akakum@...cinc.com>
>> ---
>> Changes for v5:
>> Update Calculation for HS and below bulk and isoc eps based on
>> suggestion and fixed at 2k for bulk eps considering fifo
>> constrained platforms.
>>
>> Changes for v4:
>> Updated commit message as per review comments to clarify that it has
>> been tested on specific platforms only and tried best to match all
>> expectations.
>>
>> Changes for v3:
>> Redefine logic for resizing tx fifos,added check based on  operating
>> speed and used maxp for HS and maxburst for SS  and defined max
>> allocation based on dt property.
>>
>> Changes for v2:
>> Redefine logic for resizing tx fifos, handled fifo based on  minimum
>> of maxp and maxburts.
>>
>> Changes for v1:
>> Added additional condition to allocate tx fifo for hs isoc  eps,
>> keeping the other resize logic same.
>> ---
>>   drivers/usb/dwc3/gadget.c | 20 +++++++++++++-------
>>   1 file changed, 13 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index 291bc549935b..035d49155d57 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -771,15 +771,21 @@ static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
>>   
>>   	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
>>   
>> -	if ((dep->endpoint.maxburst > 1 &&
>> -	     usb_endpoint_xfer_bulk(dep->endpoint.desc)) ||
>> -	    usb_endpoint_xfer_isoc(dep->endpoint.desc))
>> -		num_fifos = 3;
>> +	if (dwc->gadget->speed <= USB_SPEED_HIGH) {
>> +		if (usb_endpoint_xfer_bulk(dep->endpoint.desc))
>> +			num_fifos = 2;
>> +		if (usb_endpoint_xfer_isoc(dep->endpoint.desc))
>> +			num_fifos = min_t(unsigned int,
>> +					  usb_endpoint_maxp_mult(dep->endpoint.desc) + 1,
>> +					  dwc->tx_fifo_resize_max_num);
>> +	}
>>   
>> -	if (dep->endpoint.maxburst > 6 &&
>> +	if (dwc->gadget->speed > USB_SPEED_HIGH &&
>>   	    (usb_endpoint_xfer_bulk(dep->endpoint.desc) ||
>> -	     usb_endpoint_xfer_isoc(dep->endpoint.desc)) && DWC3_IP_IS(DWC31))
>> -		num_fifos = dwc->tx_fifo_resize_max_num;
>> +	     usb_endpoint_xfer_isoc(dep->endpoint.desc)))
>> +		num_fifos = min_t(unsigned int,
>> +				  dep->endpoint.maxburst,
>> +				  dwc->tx_fifo_resize_max_num);
>>   
> Do you have a default value for other endpoints?
num_fifos is initialized to 1 in beginning for other eps.
>
> Perhaps we can do something like this? What do you think?
yeah can used since we are using gadget speed only to decide and it will 
be faster as well.
>
> 	num_fifos = 1;
>
> 	switch (dwc->gadget->speed) {
> 	case USB_SPEED_SUPER_PLUS:
> 	case USB_SPEED_SUPER:
> 		if (usb_endpoint_xfer_bulk(dep->endpoint.desc) ||
> 		    usb_endpoint_xfer_isoc(dep->endpoint.desc))
> 			num_fifos = min_t(unsigned int,
> 					  dep->endpoint.maxburst,
> 					  dwc->tx_fifo_resize_max_num);
> 		break;
> 	case USB_SPEED_HIGH:
> 		if (usb_endpoint_xfer_isoc(dep->endpoint.desc)) {
> 			num_fifos = min_t(unsigned int,
> 					  usb_endpoint_maxp_mult(dep->endpoint.desc) + 1,
> 					  dwc->tx_fifo_resize_max_num);
> 			break;
> 		}
> 		fallthrough;
> 	case USB_SPEED_FULL:
> 		if (usb_endpoint_xfer_bulk(dep->endpoint.desc))
> 			num_fifos = 2;
> 		break;
> 	default:
> 		break;
> 	}
>
> Thanks,
> Thinh
>
>>   	/* FIFO size for a single buffer */
>>   	fifo = dwc3_gadget_calc_tx_fifo_size(dwc, 1);
>> -- 
>> 2.17.1
Thanks,
Akash

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