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From:   Kalle Valo <kvalo@codeaurora.org>
To:     <yhchuang@realtek.com>
Cc:     <linux-wireless@vger.kernel.org>, <johannes@sipsolutions.net>,
        <pkshih@realtek.com>, <tehuang@realtek.com>,
        <Larry.Finger@lwfinger.net>, <sgruszka@redhat.com>,
        <briannorris@chromium.org>, <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v9 05/14] rtw88: mac files
References: <1555653004-1795-1-git-send-email-yhchuang@realtek.com>
        <1555653004-1795-6-git-send-email-yhchuang@realtek.com>
Date:   Tue, 30 Apr 2019 14:48:43 +0300
In-Reply-To: <1555653004-1795-6-git-send-email-yhchuang@realtek.com>
        (yhchuang@realtek.com's message of "Fri, 19 Apr 2019 13:49:55 +0800")
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<yhchuang@realtek.com> writes:

> From: Yan-Hsuan Chuang <yhchuang@realtek.com>
>
> mac files for Realtek 802.11ac wireless network chips
>
> Reviewed-by: Stanislaw Gruszka <sgruszka@redhat.com>
> Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>

[...]

> +static int rtw_pwr_cmd_polling(struct rtw_dev *rtwdev,
> +			       struct rtw_pwr_seq_cmd *cmd)
> +{
> +	u8 value;
> +	u8 flag = 0;
> +	u32 offset;
> +	u32 cnt = RTW_PWR_POLLING_CNT;
> +
> +	if (cmd->base == RTW_PWR_ADDR_SDIO)
> +		offset = cmd->offset | SDIO_LOCAL_OFFSET;
> +	else
> +		offset = cmd->offset;
> +
> +	do {
> +		cnt--;
> +		value = rtw_read8(rtwdev, offset);
> +		value &= cmd->mask;
> +		if (value == (cmd->value & cmd->mask))
> +			return 0;
> +		if (cnt == 0) {
> +			if (rtw_hci_type(rtwdev) == RTW_HCI_TYPE_PCIE &&
> +			    flag == 0) {
> +				value = rtw_read8(rtwdev, REG_SYS_PW_CTRL);
> +				value |= BIT(3);
> +				rtw_write8(rtwdev, REG_SYS_PW_CTRL, value);
> +				value &= ~BIT(3);
> +				rtw_write8(rtwdev, REG_SYS_PW_CTRL, value);
> +				cnt = RTW_PWR_POLLING_CNT;
> +				flag = 1;
> +			} else {
> +				return -EBUSY;
> +			}
> +		} else {
> +			udelay(50);
> +		}
> +	} while (1);

Never ending loops in kernel are dangerous. I would add some kind of
fail safe to "while (1)", for example max number of loops or some time
based limit.

-- 
Kalle Valo