From: Wolfram Sang <wsa@the-dreams.de>
To: Wolfram Sang <wsa+renesas@sang-engineering.com>
Cc: linux-i2c@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@renesas.com>
Subject: Re: [PATCH 1/2] i2c: rcar: fix concurrency issue related to ICDMAER
Date: Mon, 4 Mar 2019 23:27:49 +0100 [thread overview]
Message-ID: <20190304222749.srrttj3hnsyf2cot@ninjato> (raw)
In-Reply-To: <20190303150314.6528-2-wsa+renesas@sang-engineering.com>
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> Reproduction test:
> 1. Add udelay(1) after disabling ICDMAER. (It is expected to
> generate an interrupt of rcar_i2c_irq())
>
> void rcar_i2c_dma_unmap(struct rcar_i2c_priv *priv)
> {
> ...
> rcar_i2c_write(priv, ICDMAER, 0);
> udelay(1); <-- Add this line
For the record (and self-documentation): I needed to increase the delay
and was using usleep_range(500, 800) in the end.
> ...
> priv->dma_direction = DMA_NONE;
> }
>
> 2. Execute DMA transfer.
> Performs DMA transfer of read or write. In the sample, write was used.
>
> $ i2cset -y -f 4 0x6a 0x01 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 i
And I used this command instead to make sure another message is waiting:
$ i2ctransfer -y 4 w9@0x6a 1 1+ r16
Yet, in general, I could reproduce that this patch fixes the issue, so
all is fine, I think.
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next prev parent reply other threads:[~2019-03-04 22:27 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-03 15:03 [PATCH 0/2] i2c: rcar: improve concurrency Wolfram Sang
2019-03-03 15:03 ` [PATCH 1/2] i2c: rcar: fix concurrency issue related to ICDMAER Wolfram Sang
2019-03-04 22:27 ` Wolfram Sang [this message]
2019-03-06 12:59 ` Simon Horman
2019-03-09 10:10 ` Wolfram Sang
2019-03-03 15:03 ` [PATCH 2/2] i2c: rcar: explain the lockless design Wolfram Sang
2019-03-06 12:59 ` Simon Horman
2019-03-09 10:11 ` Wolfram Sang
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