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From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
To: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: "Vinod Koul" <vinod.koul@intel.com>,
	"Geert Uytterhoeven" <geert@linux-m68k.org>,
	"Laurent Pinchart" <laurent.pinchart@ideasonboard.com>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>,
	dmaengine@vger.kernel.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Hiroyuki Yokoyama" <hiroyuki.yokoyama.vx@renesas.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Subject: Re: [PATCH v3] dmaengine: rcar-dmac: use TCRB instead of TCR for residue
Date: Mon, 6 Nov 2017 01:24:33 +0000	[thread overview]
Message-ID: <8760ao5hrp.wl%kuninori.morimoto.gx@renesas.com> (raw)
In-Reply-To: <878tfqzov2.wl%kuninori.morimoto.gx@renesas.com>


Hi Geert

> Large serial console input (copy and pasting long lines) works, as that uses
> DMA. Small serial console input (typing) doesn't work.
>
> Apparently for the serial port, TCR contains the value we need (< 0x20),
> while TCRB always contains 0x20.
> Perhaps the code should use the minimum of both registers instead?

TCR(= read) happen 1st, and TCRB (= write) happen next.
"TCRB always contains 0x20" means, DMA didn't transfer data for some reason ?

"use minimum" idea can't guarantee data transfering, same as previous topic I guess.

Best regards
---
Kuninori Morimoto

  reply	other threads:[~2017-11-06  1:24 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-19  1:15 [PATCH v3] dmaengine: rcar-dmac: use TCRB instead of TCR for residue Kuninori Morimoto
2017-10-19  7:41 ` Geert Uytterhoeven
2017-10-19 11:56 ` Laurent Pinchart
2017-10-20  6:15 ` Vinod Koul
2017-10-31 10:45   ` Geert Uytterhoeven
2017-10-31 10:46     ` Geert Uytterhoeven
2017-10-31 11:41       ` Vinod Koul
2017-11-01  3:07         ` Kuninori Morimoto
2017-11-06  1:24           ` Kuninori Morimoto [this message]
2017-11-06 13:27             ` Geert Uytterhoeven
2017-11-08  5:35         ` Vinod Koul
2017-11-08  6:33           ` Kuninori Morimoto
2017-11-08  8:37             ` Vinod Koul

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