From: Krishna Kurapati PSSNV <quic_kriskura@quicinc.com>
To: Johan Hovold <johan@kernel.org>
Cc: Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Philipp Zabel <p.zabel@pengutronix.de>,
"Andy Gross" <agross@kernel.org>,
Bjorn Andersson <andersson@kernel.org>,
"Konrad Dybcio" <konrad.dybcio@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Felipe Balbi <balbi@kernel.org>, <linux-usb@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-arm-msm@vger.kernel.org>,
<devicetree@vger.kernel.org>, <quic_pkondeti@quicinc.com>,
<quic_ppratap@quicinc.com>, <quic_wcheng@quicinc.com>,
<quic_jackp@quicinc.com>, <quic_harshq@quicinc.com>,
<ahalaney@redhat.com>
Subject: Re: [PATCH v8 3/9] usb: dwc3: core: Access XHCI address space temporarily to read port info
Date: Wed, 17 May 2023 17:51:45 +0530 [thread overview]
Message-ID: <82a8c414-bfa8-5066-fb68-1ac117b76c4e@quicinc.com> (raw)
In-Reply-To: <ZGSDr08h3Go1Dk8C@hovoldconsulting.com>
On 5/17/2023 1:05 PM, Johan Hovold wrote:
>>> You should not make another copy of xhci_find_next_ext_cap(), but rather
>>> use it directly.
>>>
>>> We already have drivers outside of usb/host using this function so it
>>> should be fine to do the same for now:
>>>
>>> #include "../host/xhci-ext-caps.h"
>
>> This was the approach which we followed when we first introduced the
>> patch [1]. But Thinh suggested to duplicate code so that we can avoid
>> any dependency on xhci (which seems to be right). So since its just one
>> function, I duplicated it here.
>
> Ok, fair enough. I still think we should not be duplicating the
> xhci definitions like this even if we were to copy the helper to avoid
> any future dependencies on xhci (it's currently an inline function,
> which is also not very nice).
>
> I'll take closer look at the rest of the series as there are a few more
> of these layering violations which we should try to avoid.
>
>>>> + offset = dwc3_xhci_find_next_ext_cap(regs, 0,
>>>> + XHCI_EXT_CAPS_PROTOCOL);
>>>> + while (offset) {
>
>>>> + temp = readl(regs + offset);
>>>> + major_revision = XHCI_EXT_PORT_MAJOR(temp);
>>>> +
>>>> + temp = readl(regs + offset + 0x08);
>
>>>> + if (major_revision == 0x03) {
>>>> + dwc->num_usb3_ports += XHCI_EXT_PORT_COUNT(temp);
>>>> + } else if (major_revision <= 0x02) {
>>>> + dwc->num_usb2_ports += XHCI_EXT_PORT_COUNT(temp);
>>>> + } else {
>>>> + dev_err(dwc->dev,
>>>> + "Unrecognized port major revision %d\n", major_revision);
>
>>> Perhaps this should be handles as in xhci core by simply warning and
>>> continuing instead.
>>>
>> I broke the loop and went to unmap as we are not sure what values would
>> be read. Any use of continuing ?
>
> Mostly to align with xhci core which currently handles this case. It
> would not not work unless you get rid of the max-ports check below
> though.
>
>>>> + ret = -EINVAL;
>>>> + goto unmap_reg;
>>>> + }
>>>> +
>>>> + offset = dwc3_xhci_find_next_ext_cap(regs, offset,
>>>> + XHCI_EXT_CAPS_PROTOCOL);
>>>> + }
>>>> +
>>>> + temp = readl(regs + DWC3_XHCI_HCSPARAMS1);
>>>> + if (HCS_MAX_PORTS(temp) != (dwc->num_usb3_ports + dwc->num_usb2_ports)) {
>>>> + dev_err(dwc->dev,
>>>> + "Mismatched reported MAXPORTS (%d)\n", HCS_MAX_PORTS(temp));
>>>> + ret = -EINVAL;
>>>> + goto unmap_reg;
>>>> + }
>>>
>>> Not sure this is needed either.
>>>
>>> Could this risk regressing platforms which does not have currently have
>>> all PHYs described in DT?
>>>
>> No, it doesn't. AFAIK, this only tells how many ports are present as per
>> the core consultant configuration of the device. I tried to explain what
>> would happen incase phy's are not present in DT in [2] & [3].
>
> Right, whether the PHYs are described in DT is not directly related to
> this.
>
> As long as HCS_MAX_PORTS by definition (assumption) is always
> (dwc->num_usb3_ports + dwc->num_usb2_ports) any such machines would
> continue to work.
>
> But if you want to catch machines where this assumption does not hold,
> you could also end up regressing machines which have so far been working
> despite these numbers not adding up.
>
> That may be acceptable, but I'm still not sure what the value of this
> check is (e.g. as xhci core will handle basic sanity checks like usb2 +
> usb3 <= max_ports).
>
Hi Johan,
Thanks for the review comments. Ideally the HCC_PARAMS1 must indicate
total number of ports supported. If not then I believe the core
consultant configuration is wrong.
According to the spec:
"The MaxPorts value in the HCSPARAMS1 register defines the number of
Port Register Sets (e.g. PORTSC, PORTPMSC, and PORTLI register sets)."
So shouldn't the (usb2+usb3 ports be equal to MaxPorts to ensure each
port properly accesses the respective PortSC etc., ?
Do we have any machines today that support HOST_ONLY_CONFIG indicated in
HWPARAMS0 that support multiport and violate this rule ?
Regards,
Krishna,
next prev parent reply other threads:[~2023-05-17 12:22 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-14 5:49 [PATCH v8 0/9] Add multiport support for DWC3 controllers Krishna Kurapati
2023-05-14 5:49 ` [PATCH v8 1/9] dt-bindings: usb: qcom,dwc3: Add bindings for SC8280 Multiport Krishna Kurapati
2023-05-14 9:46 ` Krzysztof Kozlowski
2023-05-16 10:59 ` Johan Hovold
2023-05-17 11:10 ` Krishna Kurapati PSSNV
2023-05-17 11:44 ` Johan Hovold
2023-05-17 12:19 ` Krishna Kurapati PSSNV
2023-05-17 12:55 ` Johan Hovold
2023-05-14 5:49 ` [PATCH v8 2/9] dt-bindings: usb: Add bindings for multiport properties on DWC3 controller Krishna Kurapati
2023-05-14 5:49 ` [PATCH v8 3/9] usb: dwc3: core: Access XHCI address space temporarily to read port info Krishna Kurapati
2023-05-15 21:08 ` Bjorn Andersson
2023-05-16 2:12 ` Krishna Kurapati PSSNV
2023-05-16 22:39 ` Thinh Nguyen
2023-05-16 12:11 ` Johan Hovold
2023-05-16 15:02 ` Krishna Kurapati PSSNV
2023-05-17 3:10 ` Krishna Kurapati PSSNV
2023-05-17 3:21 ` Thinh Nguyen
2023-05-17 7:46 ` Johan Hovold
2023-05-17 23:21 ` Thinh Nguyen
2023-06-07 11:56 ` Johan Hovold
2023-05-17 7:35 ` Johan Hovold
2023-05-17 12:21 ` Krishna Kurapati PSSNV [this message]
2023-05-17 15:10 ` Johan Hovold
2023-05-14 5:49 ` [PATCH v8 4/9] usb: dwc3: core: Skip setting event buffers for host only controllers Krishna Kurapati
2023-05-15 21:19 ` Bjorn Andersson
2023-05-16 12:17 ` Johan Hovold
2023-05-16 14:28 ` Krishna Kurapati PSSNV
2023-05-14 5:49 ` [PATCH v8 5/9] usb: dwc3: core: Refactor PHY logic to support Multiport Controller Krishna Kurapati
2023-05-15 21:47 ` Bjorn Andersson
2023-05-16 2:31 ` Krishna Kurapati PSSNV
2023-05-17 16:17 ` Johan Hovold
2023-05-14 5:49 ` [PATCH v8 6/9] usb: dwc3: qcom: Add multiport controller support for qcom wrapper Krishna Kurapati
2023-05-15 22:27 ` Bjorn Andersson
2023-05-16 2:19 ` Krishna Kurapati PSSNV
2023-05-17 16:37 ` Johan Hovold
2023-05-20 17:48 ` Krishna Kurapati PSSNV
2023-06-07 11:37 ` Johan Hovold
2023-06-07 19:51 ` Krishna Kurapati PSSNV
2023-06-08 9:42 ` Johan Hovold
2023-06-08 15:23 ` Krishna Kurapati PSSNV
2023-06-08 17:57 ` Thinh Nguyen
2023-06-09 8:18 ` Johan Hovold
2023-06-09 18:16 ` Thinh Nguyen
2023-06-15 4:20 ` Krishna Kurapati PSSNV
2023-06-15 21:08 ` Thinh Nguyen
2023-06-21 7:38 ` Johan Hovold
2023-06-22 4:39 ` Krishna Kurapati PSSNV
2023-06-21 7:34 ` Johan Hovold
2023-06-22 22:41 ` Thinh Nguyen
2023-05-26 2:55 ` Bjorn Andersson
2023-05-26 15:25 ` Krishna Kurapati PSSNV
2023-06-07 11:44 ` Johan Hovold
2023-06-07 19:55 ` Krishna Kurapati PSSNV
2023-06-08 9:44 ` Johan Hovold
2023-06-07 12:16 ` Johan Hovold
2023-06-27 15:43 ` Johan Hovold
2023-07-02 19:05 ` Krishna Kurapati PSSNV
2023-07-14 9:00 ` Johan Hovold
2023-07-14 10:38 ` Krishna Kurapati PSSNV
2023-07-21 11:16 ` Johan Hovold
2023-07-21 12:10 ` Konrad Dybcio
2023-07-21 12:54 ` Johan Hovold
2023-08-11 16:48 ` Konrad Dybcio
2023-08-12 8:58 ` Krishna Kurapati PSSNV
2023-05-14 5:49 ` [PATCH v8 7/9] arm64: dts: qcom: sc8280xp: Add multiport controller node for SC8280 Krishna Kurapati
2023-05-15 14:26 ` Johan Hovold
2023-05-15 15:32 ` Krishna Kurapati PSSNV
2023-05-16 10:54 ` Johan Hovold
2023-05-16 14:24 ` Krishna Kurapati PSSNV
2023-05-16 14:42 ` Johan Hovold
2023-05-16 14:44 ` Krishna Kurapati PSSNV
2023-05-14 5:49 ` [PATCH v8 8/9] arm64: dts: qcom: sa8295p: Enable tertiary controller and its 4 USB ports Krishna Kurapati
2023-05-14 5:49 ` [PATCH v8 9/9] arm64: dts: qcom: sa8540-ride: Enable first port of tertiary usb controller Krishna Kurapati
2023-05-15 2:40 ` [PATCH v8 0/9] Add multiport support for DWC3 controllers Bjorn Andersson
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