linux-kernel - Re: [PATCH v4 2/2] usb: dwc3: Add driver for Xilinx platforms

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Date:   Wed, 7 Apr 2021 14:48:11 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Manish Narani <manish.narani@...inx.com>
Cc:     gregkh@...uxfoundation.org, robh+dt@...nel.org,
        michal.simek@...inx.com, balbi@...nel.org, p.zabel@...gutronix.de,
        git@...inx.com, linux-usb@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] usb: dwc3: Add driver for Xilinx platforms

On Wed, Mar 17, 2021 at 12:22:29PM +0530, Manish Narani wrote:
> Add a new driver for supporting Xilinx platforms. This driver is used
> for some sequence of operations required for Xilinx USB controllers.
> This driver is also used to choose between PIPE clock coming from SerDes
> and the Suspend Clock. Before the controller is out of reset, the clock
> selection should be changed to PIPE clock in order to make the USB
> controller work. There is a register added in Xilinx USB controller
> register space for the same.
> 
> Signed-off-by: Manish Narani <manish.narani@...inx.com>

Trying this driver with qemu (v6.0.0-rc2) results in:

[   15.184242] dwc3-xilinx ff9d0000.usb: error -ENODEV: failed to assert Reset
[   15.185754] Unable to handle kernel paging request at virtual address 006b6b6b6b6b6b9b
[   15.185994] Mem abort info:
[   15.186065]   ESR = 0x96000004
[   15.186317]   EC = 0x25: DABT (current EL), IL = 32 bits
[   15.186414]   SET = 0, FnV = 0
[   15.186498]   EA = 0, S1PTW = 0
[   15.186579] Data abort info:
[   15.186666]   ISV = 0, ISS = 0x00000004
[   15.186756]   CM = 0, WnR = 0
[   15.186887] [006b6b6b6b6b6b9b] address between user and kernel address ranges
[   15.187436] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[   15.187777] Modules linked in:
[   15.188060] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.12.0-rc6-next-20210406-00006-g05407f068fc9-dirty #1
[   15.188265] Hardware name: Xilinx Versal Virtual development board (DT)
[   15.188495] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--)
[   15.188614] pc : __clk_put+0x24/0x138
[   15.188716] lr : __clk_put+0x24/0x138
[   15.188791] sp : ffff80001326bac0
[   15.188853] x29: ffff80001326bac0 x28: ffff00000644ed00
[   15.188982] x27: ffff00000421ecd0 x26: ffff00000421e810
[   15.189076] x25: ffff00000644f100 x24: 0000000000000000
[   15.189170] x23: ffff8000126a2570 x22: 0000000000000005
[   15.189271] x21: ffff00000644ed00 x20: ffff000006449970
[   15.189367] x19: 6b6b6b6b6b6b6b6b x18: 0000000000000010
[   15.189456] x17: 0000000000000001 x16: 0000000000000000
[   15.189546] x15: ffff000003af0490 x14: 00000000000001b7
[   15.189642] x13: ffff000003af0490 x12: 00000000ffffffea
[   15.189729] x11: ffff8000123b6460 x10: 0000000000000080
[   15.189815] x9 : 00000000676993c6 x8 : 00000000676993c6
[   15.189941] x7 : 000000007d152ab3 x6 : ffff800012768480
[   15.190047] x5 : 0000000000000000 x4 : 000000007f97631e
[   15.190139] x3 : 00000000d5bdf2c2 x2 : 000000000000000b
[   15.190233] x1 : ffff000003af0040 x0 : 0000000000000001
[   15.190432] Call trace:
[   15.190506]  __clk_put+0x24/0x138
[   15.190588]  clk_put+0x10/0x20
[   15.190653]  clk_bulk_put+0x3c/0x60
[   15.190724]  devm_clk_bulk_release+0x1c/0x28
[   15.190806]  release_nodes+0x1c0/0x2b0
[   15.190887]  devres_release_all+0x38/0x60
[   15.190963]  really_probe+0x1e4/0x3a8
[   15.191042]  driver_probe_device+0x64/0xc8
...

because of ...

> +
> +	ret = devm_clk_bulk_get_all(priv_data->dev, &priv_data->clks);
> +	if (ret < 0)
> +		return ret;
> +
...
> +
> +err_clk_put:
> +	clk_bulk_disable_unprepare(priv_data->num_clocks, priv_data->clks);
> +	clk_bulk_put_all(priv_data->num_clocks, priv_data->clks);

clk_bulk_put_all() is not necessary because of devm_clk_bulk_get_all(),
and results in a double free.

> +static int dwc3_xlnx_remove(struct platform_device *pdev)
> +{
> +	struct dwc3_xlnx	*priv_data = platform_get_drvdata(pdev);
> +	struct device		*dev = &pdev->dev;
> +
> +	of_platform_depopulate(dev);
> +
> +	clk_bulk_disable_unprepare(priv_data->num_clocks, priv_data->clks);
> +	clk_bulk_put_all(priv_data->num_clocks, priv_data->clks);

Same here. This will likely crash the driver on unload.

Guenter