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Wed, 26 Feb 2020 06:10:17 -0600 Received: from [192.168.2.6] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0327.itg.ti.com (8.15.2/8.15.2) with ESMTP id 01QCAFZf107786; Wed, 26 Feb 2020 06:10:16 -0600 Subject: Re: [PATCH v3] dmaengine: Add basic debugfs support To: Vinod Koul CC: , , , References: <20200205111557.24125-1-peter.ujfalusi@ti.com> <20200224163707.GA2618@vkoul-mobl> From: Peter Ujfalusi Message-ID: <71231b0e-a9a2-4795-da71-b484f4992278@ti.com> Date: Wed, 26 Feb 2020 14:10:14 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200224163707.GA2618@vkoul-mobl> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org Hi Vinod, On 2/24/20 6:37 PM, Vinod Koul wrote: > On 05-02-20, 13:15, Peter Ujfalusi wrote: >> Via the /sys/kernel/debug/dmaengine users can get information about the >> DMA devices and the used channels. >> >> Example output on am654-evm with audio using two channels and after running >> dmatest on 6 channels: >> >> # cat /sys/kernel/debug/dmaengine >> dma0 (285c0000.dma-controller): number of channels: 96 >> >> dma1 (31150000.dma-controller): number of channels: 267 >> dma1chan0 | 2b00000.mcasp:tx >> dma1chan1 | 2b00000.mcasp:rx >> dma1chan2 | in-use >> dma1chan3 | in-use >> dma1chan4 | in-use >> dma1chan5 | in-use >> dma1chan6 | in-use >> dma1chan7 | in-use >> >> For slave channels we can show the device and the channel name a given >> channel is requested. >> For non slave devices the only information we know is that the channel is >> in use. >> >> DMA drivers can implement the optional dbg_show callback to provide >> controller specific information instead of the generic one. >> >> It is easy to extend the generic dmaengine_dbg_show() to print additional >> information about the used channels. >> >> I have taken the idea from gpiolib. >> >> Signed-off-by: Peter Ujfalusi >> --- >> Hi, >> >> Changes since v2: >> - Use dma_chan_name() for printing the channel's name >> >> Changes since v1: >> - Use much more simplified fops for the debugfs file (via DEFINE_SHOW_ATTRIBUTE) >> - do not allow modification to dma_device_list while the debugfs file is read >> - rename the slave_name to dbg_client_name (it is only for debugging) >> - print information about dma_router if it is used by the channel >> - Formating of the output slightly changed >> >> Regards, >> Peter >> >> drivers/dma/dmaengine.c | 65 +++++++++++++++++++++++++++++++++++++++ >> include/linux/dmaengine.h | 12 +++++++- >> 2 files changed, 76 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c >> index c3b1283b6d31..37c3a4cd5b1a 100644 >> --- a/drivers/dma/dmaengine.c >> +++ b/drivers/dma/dmaengine.c >> @@ -32,6 +32,7 @@ >> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt >> >> #include >> +#include >> #include >> #include >> #include >> @@ -760,6 +761,11 @@ struct dma_chan *dma_request_chan(struct device *dev, const char *name) >> return chan ? chan : ERR_PTR(-EPROBE_DEFER); >> >> found: >> +#ifdef CONFIG_DEBUG_FS >> + chan->dbg_client_name = kasprintf(GFP_KERNEL, "%s:%s", dev_name(dev), >> + name); >> +#endif >> + >> chan->name = kasprintf(GFP_KERNEL, "dma:%s", name); >> if (!chan->name) >> return chan; >> @@ -837,6 +843,11 @@ void dma_release_channel(struct dma_chan *chan) >> chan->name = NULL; >> chan->slave = NULL; >> } >> + >> +#ifdef CONFIG_DEBUG_FS >> + kfree(chan->dbg_client_name); >> + chan->dbg_client_name = NULL; >> +#endif >> mutex_unlock(&dma_list_mutex); >> } >> EXPORT_SYMBOL_GPL(dma_release_channel); >> @@ -1562,3 +1573,57 @@ static int __init dma_bus_init(void) >> return class_register(&dma_devclass); >> } >> arch_initcall(dma_bus_init); >> + >> +#ifdef CONFIG_DEBUG_FS >> +static void dmaengine_dbg_show(struct seq_file *s, struct dma_device *dma_dev) >> +{ >> + struct dma_chan *chan; >> + >> + list_for_each_entry(chan, &dma_dev->channels, device_node) { >> + if (chan->client_count) { >> + seq_printf(s, " %-13s| %s", dma_chan_name(chan), >> + chan->dbg_client_name ?: "in-use"); >> + >> + if (chan->router) >> + seq_printf(s, " (via router: %s)\n", >> + dev_name(chan->router->dev)); >> + else >> + seq_puts(s, "\n"); >> + } >> + } >> +} >> + >> +static int dmaengine_debugfs_show(struct seq_file *s, void *data) >> +{ >> + struct dma_device *dma_dev = NULL; >> + >> + mutex_lock(&dma_list_mutex); >> + list_for_each_entry(dma_dev, &dma_device_list, global_node) { >> + seq_printf(s, "dma%d (%s): number of channels: %u\n", >> + dma_dev->dev_id, dev_name(dma_dev->dev), >> + dma_dev->chancnt); >> + >> + if (dma_dev->dbg_show) >> + dma_dev->dbg_show(s, dma_dev); > do we really want a custom dbg_show()..? Drivers can add their own > files... They could do that already ;) With the custom dbg_show() DMA drivers can save on the surrounding code and just fill in the information regarding to their HW. Again, on am654 the default information is: # cat /sys/kernel/debug/dmaengine dma0 (285c0000.dma-controller): number of channels: 96 dma1 (31150000.dma-controller): number of channels: 267 dma1chan0 | 2b00000.mcasp:tx dma1chan1 | 2b00000.mcasp:rx dma1chan2 | in-use dma1chan3 | in-use dma1chan4 | in-use dma1chan5 | in-use With my current .dbg_show implementation for k3-udma: # cat /sys/kernel/debug/dmaengine dma0 (285c0000.dma-controller): number of channels: 96 dma1 (31150000.dma-controller): number of channels: 267 dma1chan0 | 2b00000.mcasp:tx (MEM_TO_DEV, tchan8 [0x1008 -> 0xc400], PDMA, TR mode) dma1chan1 | 2b00000.mcasp:rx (DEV_TO_MEM, rchan8 [0x4400 -> 0x9008], PDMA, TR mode) dma1chan2 | in-use (MEM_TO_MEM, chan2 pair [0x1002 -> 0x9002], PSI-L Native, TR mode) dma1chan3 | in-use (MEM_TO_MEM, chan3 pair [0x1003 -> 0x9003], PSI-L Native, TR mode) dma1chan4 | in-use (MEM_TO_MEM, chan4 pair [0x1004 -> 0x9004], PSI-L Native, TR mode) dma1chan5 | in-use (MEM_TO_MEM, chan5 pair [0x1005 -> 0x9005], PSI-L Native, TR mode) For me this makes a huge difference. > >> + else >> + dmaengine_dbg_show(s, dma_dev); >> + >> + if (!list_is_last(&dma_dev->global_node, &dma_device_list)) >> + seq_puts(s, "\n"); >> + } >> + mutex_unlock(&dma_list_mutex); >> + >> + return 0; >> +} >> +DEFINE_SHOW_ATTRIBUTE(dmaengine_debugfs); >> + >> +static int __init dmaengine_debugfs_init(void) >> +{ >> + /* /sys/kernel/debug/dmaengine */ >> + debugfs_create_file("dmaengine", 0444, NULL, NULL, >> + &dmaengine_debugfs_fops); > > Should we add a directory? That way we can keep adding stuff into that > one and have this file as 'summary' underneath? I like the fact hat I can get all the information via one file. Saves a lot of time (and explaining to users) on finding the correct one to cat... - Péter Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki