RE: [PATCH v3 4/4] rtw88: Fix Sparse warning for rtw8821c_hw_spec

[Ping-Ke Shih <pkshih@realtek.com>]

> -----Original Message-----
> From: Kalle Valo <kvalo@kernel.org>
> Sent: Wednesday, June 8, 2022 3:45 PM
> To: Ping-Ke Shih <pkshih@realtek.com>
> Cc: Larry Finger <Larry.Finger@lwfinger.net>; Nathan Chancellor <nathan@kernel.org>; Johannes Berg
> <johannes@sipsolutions.net>; linux-wireless@vger.kernel.org
> Subject: Re: [PATCH v3 4/4] rtw88: Fix Sparse warning for rtw8821c_hw_spec
> 
> Ping-Ke Shih <pkshih@realtek.com> writes:
> 
> >
> > The ch_param[3] is only used by 8821c, so it doesn't affect other devices.
> > I will prepare a patch to fix it.
> 
> But why didn't the compiler catch this? Is there some evil cast
> somewhere which removes the const? We should fix that as well (in a
> separate patch).
> 

This is because we assign a const to .driver_data that is non-const kernel_ulong_t:

static const struct pci_device_id rtw_8821ce_id_table[] = {
	{
		.driver_data = (kernel_ulong_t)&rtw8821c_hw_spec
	},

When casting it back in pci_probe(), we need to add 'const' after Larry's patches:

rtwdev->chip = (struct rtw_chip_info *)id->driver_data;


I will prepare another patch to fix that.

Ping-Ke