Messages in this thread | | | From | Harini Katakam <> | Date | Fri, 31 Jan 2020 21:44:20 +0530 | Subject | Re: [PATCH 2/2] net: macb: Limit maximum GEM TX length in TSO |
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Hi Claudiu,
On Fri, Jan 31, 2020 at 8:27 PM <Claudiu.Beznea@microchip.com> wrote: > > > > On 31.01.2020 12:27, Harini Katakam wrote: > > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > > > GEM_MAX_TX_LEN currently resolves to 0x3FF8 for any IP version supporting > > TSO with full 14bits of length field in payload descriptor. But an IP > > errata causes false amba_error (bit 6 of ISR) when length in payload > > descriptors is specified above 16387. The error occurs because the DMA > > falsely concludes that there is not enough space in SRAM for incoming > > payload. These errors were observed continuously under stress of large > > packets using iperf on a version where SRAM was 16K for each queue. This > > errata will be documented shortly and affects all versions since TSO > > functionality was added. Hence limit the max length to 0x3FC0 (rounded). > > > > Signed-off-by: Harini Katakam <harini.katakam@xilinx.com> > > --- <snip> > > - bp->max_tx_length = GEM_MAX_TX_LEN; > > + bp->max_tx_length = min(GEM_MAX_TX_LEN, GEM_MAX_TX_LEN_ERRATA); > > Isn't this always resolved to GEM_MAX_TX_LEN_ERRATA?
Sorry, yes it does. I accidentally concluded that this was version specific. Will just default to 0x3fc0 in v2. Thanks for the review.
Regards, Harini
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