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Message-ID: <279a54f2-7260-4270-83c7-d6f5c5ba0873@quicinc.com>
Date: Fri, 20 Oct 2023 15:12:44 +0530
From: Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
To: Johan Hovold <johan@...nel.org>
CC: Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Philipp Zabel <p.zabel@...gutronix.de>,
"Andy Gross" <agross@...nel.org>,
Bjorn Andersson <andersson@...nel.org>,
"Konrad Dybcio" <konrad.dybcio@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Felipe Balbi <balbi@...nel.org>,
Wesley Cheng <quic_wcheng@...cinc.com>,
<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
<quic_pkondeti@...cinc.com>, <quic_ppratap@...cinc.com>,
<quic_jackp@...cinc.com>, <ahalaney@...hat.com>,
<quic_shazhuss@...cinc.com>
Subject: Re: [PATCH v13 01/10] usb: dwc3: core: Access XHCI address space
temporarily to read port info
On 10/20/2023 2:02 PM, Johan Hovold wrote:
> On Sat, Oct 07, 2023 at 09:17:57PM +0530, Krishna Kurapati wrote:
>> Currently host-only capable DWC3 controllers support Multiport.
>
> You use the word "currently" in a few places like this (e.g. in comments
> in the code). What exactly do you mean? That all current multiport
> controllers are host-only, or that this is all that the driver supports
> after your changes?
>
This means that, today the capable multiport controllers are host-only
capable, not that the driver is designed that way.
> Please rephrase accordingly throughout so that this becomes clear.
>
> In any case it looks like the above sentence is at least missing an
> "only".
>
>> +static int dwc3_read_port_info(struct dwc3 *dwc)
>> +{
>> + void __iomem *base;
>> + u8 major_revision;
>> + u32 offset = 0;
>
> I'd move the initialisation just before the loop.
>
>> + u32 val;
>> +
>> + /*
>> + * Remap xHCI address space to access XHCI ext cap regs,
>
> Drop comma and merge with next line and break it closer to 80 chars
> (instead of 65).
>
>> + * since it is needed to get port info.
>
> s/since it is needed to get/which hold the/?
>
>> + */
>> + base = ioremap(dwc->xhci_resources[0].start,
>> + resource_size(&dwc->xhci_resources[0]));
>> + if (IS_ERR(base))
>> + return PTR_ERR(base);
>> +
>> + do {
>> + offset = xhci_find_next_ext_cap(base, offset,
>> + XHCI_EXT_CAPS_PROTOCOL);
>> + if (!offset)
>> + break;
>> +
>> + val = readl(base + offset);
>> + major_revision = XHCI_EXT_PORT_MAJOR(val);
>> +
>> + val = readl(base + offset + 0x08);
>> + if (major_revision == 0x03) {
>> + dwc->num_usb3_ports += XHCI_EXT_PORT_COUNT(val);
>> + } else if (major_revision <= 0x02) {
>> + dwc->num_usb2_ports += XHCI_EXT_PORT_COUNT(val);
>> + } else {
>> + dev_err(dwc->dev,
>
> This should be dev_warn() (as in the xhci driver) now that you no longer
> treat it as a fatal error.
>
>> + "Unrecognized port major revision %d\n",
>
> Merge this with the previous line (even if it makes that line 83 chars).
>
> Use a lower case 'U' for consistency with most of the error messages.
>
Sure, will change this to dev_warn and modify the "u".
>> + major_revision);
>> + }
>> + } while (1);
>> +
>> + dev_dbg(dwc->dev, "hs-ports: %u ss-ports: %u\n",
>> + dwc->num_usb2_ports, dwc->num_usb3_ports);
>> +
>> + iounmap(base);
>> +
>> + return 0;
>> +}
>> +
>> static int dwc3_probe(struct platform_device *pdev)
>> {
>> struct device *dev = &pdev->dev;
>> @@ -1846,6 +1892,7 @@ static int dwc3_probe(struct platform_device *pdev)
>> void __iomem *regs;
>> struct dwc3 *dwc;
>> int ret;
>> + unsigned int hw_mode;
>
> Nit: I'd place this one before ret.
> >>
>> dwc = devm_kzalloc(dev, sizeof(*dwc), GFP_KERNEL);
>> if (!dwc)
>> @@ -1926,6 +1973,20 @@ static int dwc3_probe(struct platform_device *pdev)
>> goto err_disable_clks;
>> }
>>
>> + /*
>> + * Currently only DWC3 controllers that are host-only capable
>> + * support Multiport.
>> + */
>
> So is this is a limitation of the hardware or implementation?
>
This is how the hardware is implemented today. I wanted to convey that
"lets check for host-only condition before going for reading port info"
>> + hw_mode = DWC3_GHWPARAMS0_MODE(dwc->hwparams.hwparams0);
>> + if (hw_mode == DWC3_GHWPARAMS0_MODE_HOST) {
>> + ret = dwc3_read_port_info(dwc);
>> + if (ret)
>> + goto err_disable_clks;
>> + } else {
>> + dwc->num_usb2_ports = 1;
>> + dwc->num_usb3_ports = 1;
>> + }
>> +
>> spin_lock_init(&dwc->lock);
>> mutex_init(&dwc->mutex);
>
> Johan
>
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