From: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
To: Wesley Cheng <wcheng@codeaurora.org>
Cc: Felipe Balbi <balbi@kernel.org>,
Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
"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>,
"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: Tue, 20 Jul 2021 13:41:20 +0200 [thread overview]
Message-ID: <YPa2YL2mfffiz4i4@kroah.com> (raw)
In-Reply-To: <6bc35b95-8386-1a6b-46dd-f33035e6dee5@codeaurora.org>
On Wed, Jul 14, 2021 at 12:30:07AM -0700, Wesley Cheng wrote:
>
>
> 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.
Any hint as to when these fixups will be sent?
thanks,
greg k-h
next prev parent reply other threads:[~2021-07-20 11:46 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
2021-07-20 11:41 ` gregkh [this message]
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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