linux-kernel - Re: [RFC PATCH] staging: rtl8723au: fix byte order problems

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Message-ID: <CAGRGNgXxO2ZAGob=p83dNw+98kgZyYKdGcrh8m-vxXo+a7ezMw@mail.gmail.com>
Date:	Tue, 5 Jan 2016 08:57:56 +1100
From:	Julian Calaby <julian.calaby@...il.com>
To:	Sven Dziadek <sven.dziadek@....de>
Cc:	Larry Finger <Larry.Finger@...inger.net>,
	Jes Sorensen <Jes.Sorensen@...hat.com>,
	Greg KH <gregkh@...uxfoundation.org>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] staging: rtl8723au: fix byte order problems

Hi Sven,

On Tue, Jan 5, 2016 at 2:29 AM, Sven Dziadek <sven.dziadek@....de> wrote:
> diff --git a/drivers/staging/rtl8723au/hal/rtl8723a_cmd.c b/drivers/staging/rtl8723au/hal/rtl8723a_cmd.c
> index 1662c03c..57f5941 100644
> --- a/drivers/staging/rtl8723au/hal/rtl8723a_cmd.c
> +++ b/drivers/staging/rtl8723au/hal/rtl8723a_cmd.c
> @@ -93,11 +93,9 @@ int FillH2CCmd(struct rtw_adapter *padapter, u8 ElementID, u32 CmdLen,
>
>                 if (h2c_cmd & BIT(7)) {
>                         msgbox_ex_addr = REG_HMEBOX_EXT_0 + (h2c_box_num * EX_MESSAGE_BOX_SIZE);
> -                       h2c_cmd_ex = le16_to_cpu(h2c_cmd_ex);
>                         rtl8723au_write16(padapter, msgbox_ex_addr, h2c_cmd_ex);
>                 }
>                 msgbox_addr = REG_HMEBOX_0 + (h2c_box_num * MESSAGE_BOX_SIZE);
> -               h2c_cmd = le32_to_cpu(h2c_cmd);
>                 rtl8723au_write32(padapter, msgbox_addr, h2c_cmd);

While Jes has NACK'd this change, it does highlight that the h2c_cmd
and h2c_cmd_ex variables are being used to hold both cpu-endian and
little-endian data. A worthwhile change here might be to move the
conversion into the function call following these lines so that they
remain "clean".

That said, I'm not sure this particular snippet of code would work on
big-endian at all as I'm pretty sure that BIT() produces cpu-endian
values and we know from the line you remove that h2c_cmd is
little-endian at this point.

Thanks,

-- 
Julian Calaby

Email: julian.calaby@...il.com
Profile: http://www.google.com/profiles/julian.calaby/
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