Re: [PATCH v1 1/3] soc/tegra: fuse: Fix reading registers using DMA on Tegra20

[Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

Hi Dmitry,

On 25/09/17 23:35, Dmitry Osipenko wrote:
> DMA config is incorrect, because of it DMA transfer is never issued and
> tegra20_fuse_read() always returns 0x0.
> 
> Signed-off-by: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/soc/tegra/fuse/fuse-tegra.c   | 1 +
>  drivers/soc/tegra/fuse/fuse-tegra20.c | 3 ++-
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/tegra/fuse/fuse-tegra.c b/drivers/soc/tegra/fuse/fuse-tegra.c
> index b7c552e3133c..73a3a2c74021 100644
> --- a/drivers/soc/tegra/fuse/fuse-tegra.c
> +++ b/drivers/soc/tegra/fuse/fuse-tegra.c
> @@ -132,6 +132,7 @@ static int tegra_fuse_probe(struct platform_device *pdev)
>  
>  	/* take over the memory region from the early initialization */
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	fuse->phys = res->start;
>  	fuse->base = devm_ioremap_resource(&pdev->dev, res);
>  	if (IS_ERR(fuse->base))
>  		return PTR_ERR(fuse->base);
> diff --git a/drivers/soc/tegra/fuse/fuse-tegra20.c b/drivers/soc/tegra/fuse/fuse-tegra20.c
> index 294413a969a0..a33f48c06771 100644
> --- a/drivers/soc/tegra/fuse/fuse-tegra20.c
> +++ b/drivers/soc/tegra/fuse/fuse-tegra20.c
> @@ -59,7 +59,7 @@ static u32 tegra20_fuse_read(struct tegra_fuse *fuse, unsigned int offset)
>  
>  	mutex_lock(&fuse->apbdma.lock);
>  
> -	fuse->apbdma.config.src_addr = fuse->apbdma.phys + FUSE_BEGIN + offset;
> +	fuse->apbdma.config.src_addr = fuse->phys + FUSE_BEGIN + offset;
>  
>  	err = dmaengine_slave_config(fuse->apbdma.chan, &fuse->apbdma.config);
>  	if (err)
> @@ -119,6 +119,7 @@ static int tegra20_fuse_probe(struct tegra_fuse *fuse)
>  	fuse->apbdma.config.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
>  	fuse->apbdma.config.src_maxburst = 1;
>  	fuse->apbdma.config.dst_maxburst = 1;
> +	fuse->apbdma.config.direction = DMA_DEV_TO_MEM;
>  
>  	init_completion(&fuse->apbdma.wait);
>  	mutex_init(&fuse->apbdma.lock);

Thanks for the fix.

When booting the mainline on Tegra20 Trimslice, I only see the
tegra20_fuse_read_early() called and not the tegra20_fuse_read(). That's
not to say it is not needed, but I am wondering if we really need this
complex tegra20_fuse_read() using DMA and whether we should just have
the normal fuse->read() call tegra20_fuse_read_early() as well to
simplify matters?

Maybe Thierry or Stephen know the history here?

As far as the fix is concerned ...

Reviewed-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

Cheers
Jon

-- 
nvpublic