Re: [PATCH] wifi: rtl8xxxu: correct the error value of 'timeout'

[Su Hui]

On 2023/11/14 14:42, Ping-Ke Shih wrote:
> > -----Original Message-----
> > From: Su Hui <suhui@xxxxxxxxxxxx>
> > Sent: Monday, November 13, 2023 1:49 PM
> > To: Jes.Sorensen@xxxxxxxxx; kvalo@xxxxxxxxxx
> > Cc: Su Hui <suhui@xxxxxxxxxxxx>; linux-wireless@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > kernel-janitors@xxxxxxxxxxxxxxx
> > Subject: [PATCH] wifi: rtl8xxxu: correct the error value of 'timeout'
> >
> > When 'rtl8xxxu_dma_agg_pages <= page_thresh', 'timeout' should equal to
> > 'page_thresh' rather than '4'. Change the code order to fix this problem.
> >
> > Fixes: 614e389f36a9 ("rtl8xxxu: gen1: Set aggregation timeout (REG_RXDMA_AGG_PG_TH + 1) as well")
> I think this should fix
> Fixes: fd83f1227826 ("rtl8xxxu: gen1: Add module parameters to adjust DMA aggregation parameters")
Agreed. Thanks for your reminder!
> > Signed-off-by: Su Hui <suhui@xxxxxxxxxxxx>
> > ---
> >   .../net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c    | 12 ++++++------
> >   1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > index 43ee7592bc6e..9cab8b1dc486 100644
> > --- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > +++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
> > @@ -4757,6 +4757,12 @@ void rtl8xxxu_gen1_init_aggregation(struct rtl8xxxu_priv *priv)
> >           *   RxAggPageTimeout = 4 or 6 (absolute time 34ms/(2^6))
> >           */
> >
> > +       /* REG_RXDMA_AGG_PG_TH + 1 seems to be the timeout register on
> > +        * gen2 chips and rtl8188eu. The rtl8723au seems unhappy if we
> > +        * don't set it, so better set both.
> > +        */
> > +       timeout = 4;
> > +
> >          page_thresh = (priv->fops->rx_agg_buf_size / 512);
> >          if (rtl8xxxu_dma_agg_pages >= 0) {
> >                  if (rtl8xxxu_dma_agg_pages <= page_thresh)
> The logic here is:
>
> 	page_thresh = (priv->fops->rx_agg_buf_size / 512);
> 	if (rtl8xxxu_dma_agg_pages >= 0) {
> 		if (rtl8xxxu_dma_agg_pages <= page_thresh)
> 			timeout = page_thresh;
>
> Do you know why 'timeout = page_thresh;'? Intuitively, units of 'timeout' and
> 'thresh' are different. Maybe, we should correct here instead?
I don't know the reason about this. :(
I found this error because clang static checker complains about this 
code that value stored to 'timeout'
is never read.

Su Hui