From: EnDe Tan <ende.tan@starfivetech.com>
To: Vinod Koul <vkoul@kernel.org>
Cc: "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
"Eugeniy.Paltsev@synopsys.com" <Eugeniy.Paltsev@synopsys.com>
Subject: RE: [v2,1/1] dmaengine: dw-axi-dmac: Support src_maxburst and dst_maxburst
Date: Mon, 6 Nov 2023 08:44:02 +0000 [thread overview]
Message-ID: <5c6b1d6c73ff4b558457bf248a0d0bb0@EXMBX061.cuchost.com> (raw)
In-Reply-To: <ZR1optUInIcCgTxN@matsya>
> Are client drivers setting this today, will there be regression if not set?
I don't see any dw-axi-dmac client driver setting this src_maxburt/dst_maxburst explicitly.
This means that all the while, those client drivers have been using the default value of DWAXIDMAC_BURST_TRANS_LEN_4.
In the patch, to maintain this backward compatibility, ternary operator is used, for example:
> > + dst_burst_trans_len = chan->config.dst_maxburst ?
> > + __ffs(chan->config.dst_maxburst) - 1 :
> > + DWAXIDMAC_BURST_TRANS_LEN_4;
so that if src_maxburst/dst_maxburst is not set, default value of DWAXIDMAC_BURST_TRANS_LEN_4 applies.
> this is wrong, memcpy should never use slave config value. These values are
> for peripheral and not meant for mem-mem transfers
Agreed, thanks for pointing that out. It shall be removed in patch v3.
prev parent reply other threads:[~2023-11-06 8:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-13 11:04 [v2,1/1] dmaengine: dw-axi-dmac: Support src_maxburst and dst_maxburst Tan En De
2023-10-04 13:29 ` Vinod Koul
2023-11-06 8:44 ` EnDe Tan [this message]
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