From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Hunter Subject: Re: [PATCH v1 1/3] soc/tegra: fuse: Fix reading registers using DMA on Tegra20 Date: Tue, 26 Sep 2017 15:08:51 +0100 Message-ID: <87d33561-d959-7444-552d-7226adf29eb4@nvidia.com> References: <27dadd0335aac71c9d4d613c33a6a1d0a285afa4.1506378772.git.digetx@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <27dadd0335aac71c9d4d613c33a6a1d0a285afa4.1506378772.git.digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Content-Language: en-US Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dmitry Osipenko , Thierry Reding Cc: linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Stephen Warren List-Id: linux-tegra@vger.kernel.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 > --- > 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 Cheers Jon -- nvpublic