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From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Michael Olbrich <m.olbrich@pengutronix.de>,
	Lucas Stach <l.stach@pengutronix.de>,
	Vinod Koul <vkoul@kernel.org>
Cc: dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	Dan Williams <dan.j.williams@intel.com>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>
Subject: Re: [PATCH v2] dmaengine: imx-sdma: fix incorrect conversion to readl_relaxed_poll_timeout_atomic()
Date: Sat, 22 Jun 2019 20:26:53 +0100
Message-ID: <20190622192653.puxds354sx5v3jg7@shell.armlinux.org.uk> (raw)
In-Reply-To: <E1helB3-0005d6-7m@rmk-PC.armlinux.org.uk>

Well, this doesn't appear to completely solve the problem either -
one out of four of my platforms still spat out the error (because
the SDMA initialisation can run on a different CPU to that which
receives the interrupt.)

I've thought about using a completion, but that doesn't work either,
because in the case of a single CPU, the interrupts will be masked,
so we can't wait for completion.  I think we need to eliminate that
spinlock around this code.

On Sat, Jun 22, 2019 at 07:55:53PM +0100, Russell King wrote:
> When imx-sdma was converted to use readl_relaxed_poll_timeout_atomic(),
> the termination condition was inverted.  Fix this.
> 
> Fixes: 1d069bfa3c78 ("dmaengine: imx-sdma: ack channel 0 IRQ in the interrupt handler")
> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
> ---
>  drivers/dma/imx-sdma.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index 5f3c1378b90e..c45cbdb09714 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -655,15 +655,21 @@ static void sdma_enable_channel(struct sdma_engine *sdma, int channel)
>  static int sdma_run_channel0(struct sdma_engine *sdma)
>  {
>  	int ret;
> -	u32 reg;
> +	u32 reg, mask;
> +
> +	// Disable channel 0 interrupt
> +	mask = readl_relaxed(sdma->regs + SDMA_H_INTRMSK);
> +	writel_relaxed(mask & ~1, sdma->regs + SDMA_H_INTRMSK);
>  
>  	sdma_enable_channel(sdma, 0);
>  
> -	ret = readl_relaxed_poll_timeout_atomic(sdma->regs + SDMA_H_STATSTOP,
> -						reg, !(reg & 1), 1, 500);
> +	ret = readl_relaxed_poll_timeout_atomic(sdma->regs + SDMA_H_INTR,
> +						reg, reg & 1, 1, 500);
>  	if (ret)
>  		dev_err(sdma->dev, "Timeout waiting for CH0 ready\n");
>  
> +	writel_relaxed(mask, sdma->regs + SDMA_H_INTRMSK);
> +
>  	/* Set bits of CONFIG register with dynamic context switching */
>  	reg = readl(sdma->regs + SDMA_H_CONFIG);
>  	if ((reg & SDMA_H_CONFIG_CSM) == 0) {
> -- 
> 2.7.4
> 
> 

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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  reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-22 16:53 [BUG] imx-sdma: readl_relaxed_poll_timeout_atomic() conversion Russell King - ARM Linux admin
2019-06-22 18:02 ` [PATCH] dmaengine: imx-sdma: fix incorrect conversion to readl_relaxed_poll_timeout_atomic() Russell King
2019-06-22 18:10 ` [BUG] imx-sdma: readl_relaxed_poll_timeout_atomic() conversion Michael Olbrich
2019-06-22 18:42   ` Russell King - ARM Linux admin
2019-06-22 18:51     ` Russell King - ARM Linux admin
2019-06-24 12:14     ` Lucas Stach
2019-06-24 12:15       ` Russell King - ARM Linux admin
2019-06-24 12:52         ` Lucas Stach
2019-06-22 18:55 ` [PATCH v2] dmaengine: imx-sdma: fix incorrect conversion to readl_relaxed_poll_timeout_atomic() Russell King
2019-06-22 19:26   ` Russell King - ARM Linux admin [this message]
2019-06-22 20:26     ` Russell King - ARM Linux admin
2019-06-23 13:29       ` Fabio Estevam
2019-06-25  9:00         ` Robin Gong

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