Messages in this thread | | | From | Ping-Ke Shih <> | Subject | RE: wifi: rtw88: question about SDIO RX aggregation limiting | Date | Tue, 20 Jun 2023 05:26:20 +0000 |
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> -----Original Message----- > From: Martin Blumenstingl <martin.blumenstingl@googlemail.com> > Sent: Tuesday, June 20, 2023 4:38 AM > To: Ping-Ke Shih <pkshih@realtek.com> > Cc: linux-wireless@vger.kernel.org; Lukas F. Hartmann <lukas@mntre.com>; linux-kernel@vger.kernel.org; > tony0620emma@gmail.com; jernej.skrabec@gmail.com > Subject: Re: wifi: rtw88: question about SDIO RX aggregation limiting > > Hello Ping-Ke, > > apologies for the long delay. > > On Tue, Jun 13, 2023 at 4:20 AM Ping-Ke Shih <pkshih@realtek.com> wrote: > [...] > > The unit of BIT_RXDMA_AGG_PG_TH is 1k bytes, so I think you can > > set mmc_host->max_req_size/1024. > I tried this but I got a result that I don't understand. > I've been testing with three BIT_RXDMA_AGG_PG_TH values on a SoC that > can handle 255 * 1024 bytes. Each time I connected to the same AP and > downloaded a bigger file over http(s). > BIT_RXDMA_AGG_PG_TH: biggest observed rx_len in rtw_sdio_rxfifo_recv() > 255: 20968 > 6: 5122 > 1: 1602
Please also print out number of packets you receive, and then we can see how many packets aggregate.
> > The biggest rx_len I have observed for BIT_RXDMA_AGG_PG_TH 1 looks suspicious: > My understanding is that I shouldn't be seeing rx_len larger than > BIT_RXDMA_AGG_PG_TH * 1024. > BIT_RXDMA_AGG_PG_TH = 6 is within this limit but BIT_RXDMA_AGG_PG_TH = > 1 isn't (I'm seeing 578 extra bytes in addition to the 1024 bytes that > I was expecting).
Assume threshold is 1k, and single one packet is larger than 1k. Hardware will not split it into two. Also, please make sure 0x280[29] BIT_EN_PRE_CALC is 1. Otherwise, it will possibly aggregate additional one packet to over the threshold.
0x280[15:8] is timeout time in unit of 1us for SDIO interface. When set threshold to 255, you can enlarge this to see if it can aggregate more as expected.
> Do you have any idea where this is coming from? I'm worried that we > can still end up with the problem that Lukas described but seems to > not have hit in his testing with BIT_RXDMA_AGG_PG_TH = 6 > > > I wonder why 0x6 works on Amlogic SoCs. Could you or Lukas compare performance > > between the settings of 0x1 and 0x6? > I can do this later this week but I'd like to understand the above > results first. >
Ping-Ke
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