From: Wesley Cheng <wcheng@codeaurora.org>
To: Felipe Balbi <balbi@kernel.org>,
Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"agross@kernel.org" <agross@kernel.org>,
"bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
"frowand.list@gmail.com" <frowand.list@gmail.com>
Cc: "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"jackp@codeaurora.org" <jackp@codeaurora.org>
Subject: Re: [PATCH v14 3/6] usb: dwc3: Resize TX FIFOs to meet EP bursting requirements
Date: Wed, 14 Jul 2021 00:30:07 -0700 [thread overview]
Message-ID: <6bc35b95-8386-1a6b-46dd-f33035e6dee5@codeaurora.org> (raw)
In-Reply-To: <877dhtz9de.fsf@kernel.org>
On 7/13/2021 11:40 PM, Felipe Balbi wrote:
>
> Hi,
>
> Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
>>> Thinh Nguyen <Thinh.Nguyen@synopsys.com> writes:
>>>> Wesley Cheng wrote:
>>>>> Some devices have USB compositions which may require multiple endpoints
>>>>> that support EP bursting. HW defined TX FIFO sizes may not always be
>>>>> sufficient for these compositions. By utilizing flexible TX FIFO
>>>>> allocation, this allows for endpoints to request the required FIFO depth to
>>>>> achieve higher bandwidth. With some higher bMaxBurst configurations, using
>>>>> a larger TX FIFO size results in better TX throughput.
>>>>>
>>>>> By introducing the check_config() callback, the resizing logic can fetch
>>>>> the maximum number of endpoints used in the USB composition (can contain
>>>>> multiple configurations), which helps ensure that the resizing logic can
>>>>> fulfill the configuration(s), or return an error to the gadget layer
>>>>> otherwise during bind time.
>>>>>
>>>>> Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
>>>>> ---
>>>>> drivers/usb/dwc3/core.c | 15 +++
>>>>> drivers/usb/dwc3/core.h | 16 ++++
>>>>> drivers/usb/dwc3/ep0.c | 2 +
>>>>> drivers/usb/dwc3/gadget.c | 232 ++++++++++++++++++++++++++++++++++++++++++++++
>>>>> 4 files changed, 265 insertions(+)
>>>>>
>>>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>>>> index ba74ad7..b194aecd 100644
>>>>> --- a/drivers/usb/dwc3/core.c
>>>>> +++ b/drivers/usb/dwc3/core.c
>>>>> @@ -1267,6 +1267,7 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>>>>> u8 rx_max_burst_prd;
>>>>> u8 tx_thr_num_pkt_prd;
>>>>> u8 tx_max_burst_prd;
>>>>> + u8 tx_fifo_resize_max_num;
>>>>> const char *usb_psy_name;
>>>>> int ret;
>>>>>
>>>>> @@ -1282,6 +1283,13 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>>>>> */
>>>>> hird_threshold = 12;
>>>>>
>>>>> + /*
>>>>> + * default to a TXFIFO size large enough to fit 6 max packets. This
>>>>> + * allows for systems with larger bus latencies to have some headroom
>>>>> + * for endpoints that have a large bMaxBurst value.
>>>>> + */
>>>>> + tx_fifo_resize_max_num = 6;
>>>>> +
>>>>> dwc->maximum_speed = usb_get_maximum_speed(dev);
>>>>> dwc->max_ssp_rate = usb_get_maximum_ssp_rate(dev);
>>>>> dwc->dr_mode = usb_get_dr_mode(dev);
>>>>> @@ -1325,6 +1333,11 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>>>>> &tx_thr_num_pkt_prd);
>>>>> device_property_read_u8(dev, "snps,tx-max-burst-prd",
>>>>> &tx_max_burst_prd);
>>>>> + dwc->do_fifo_resize = device_property_read_bool(dev,
>>>>> + "tx-fifo-resize");
>>>>> + if (dwc->do_fifo_resize)
>>>>> + device_property_read_u8(dev, "tx-fifo-max-num",
>>>>> + &tx_fifo_resize_max_num);
>>>>
>>>> Why is this check here? The dwc->tx_fifo_resize_max_num should store
>>>> whatever property the user sets. Whether the driver wants to use this
>>>
>>> Ack!
>>>
>>>> property should depend on "dwc->do_fifo_resize". Also why don't we have
>>>> "snps," prefix to be consistent with the other properties?
>>>
>>> Ack!
>>>
>>>> Can we enforce to a single property? If the designer wants to enable
>>>> this feature, he/she can to provide the tx-fifo-max-num. This would
>>>> simplify the driver a bit. Since this is to optimize for performance,
>>>> the user should know/want/test the specific value if they want to set
>>>> for their setup and not hoping that the default setting not break their
>>>> setup. So we can remove the "do_fifo_resize" property and just check
>>>> whether tx_fifo_resize_max_num is set.
>>>
>>> Ack!
>>>
>>> All very valid points :-)
>>>
Hi Thinh/Felipe,
>>
>> Looks like this series already landed in Greg's testing branch. Not sure
>> how we usually handle this to address some of our concerns. Add fix
>> patches on top of Greg's testing branch?
>
> yup, no choice anymore :-(
>
Let me review your feedback, which had some good points. We can add a
change addressing everything on top of what is merged on Greg's branch.
Thanks for all the input!
Thanks
Wesley Cheng
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2021-07-14 7:30 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-10 9:13 [PATCH v14 0/6] Re-introduce TX FIFO resize for larger EP bursting Wesley Cheng
2021-07-10 9:13 ` [PATCH v14 1/6] usb: gadget: udc: core: Introduce check_config to verify USB configuration Wesley Cheng
2021-07-10 9:13 ` [PATCH v14 2/6] usb: gadget: configfs: Check USB configuration before adding Wesley Cheng
2021-07-10 9:13 ` [PATCH v14 3/6] usb: dwc3: Resize TX FIFOs to meet EP bursting requirements Wesley Cheng
2021-07-12 23:38 ` Thinh Nguyen
2021-07-13 8:39 ` Felipe Balbi
2021-07-14 2:58 ` Thinh Nguyen
2021-07-14 3:10 ` Thinh Nguyen
2021-07-14 6:40 ` Felipe Balbi
2021-07-14 6:52 ` gregkh
2021-07-14 7:30 ` Wesley Cheng [this message]
2021-07-20 11:41 ` gregkh
2021-07-21 6:23 ` Wesley Cheng
2021-07-14 6:51 ` gregkh
2021-07-14 2:59 ` Thinh Nguyen
2021-07-10 9:13 ` [PATCH v14 4/6] of: Add stub for of_add_property() Wesley Cheng
2021-07-10 9:13 ` [PATCH v14 5/6] usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by default Wesley Cheng
2021-07-10 9:13 ` [PATCH v14 6/6] dt-bindings: usb: dwc3: Update dwc3 TX fifo properties Wesley Cheng
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