linux-kernel - [PATCH v5 0/3] dmaengine: Initial debugfs support

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Message-ID: <20200306142839.17910-1-peter.ujfalusi@ti.com>
Date:   Fri, 6 Mar 2020 16:28:36 +0200
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     <vkoul@...nel.org>
CC:     <dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <dan.j.williams@...el.com>, <geert@...ux-m68k.org>
Subject: [PATCH v5 0/3]  dmaengine: Initial debugfs support

Hi,

Changes sicne v4:
- Move the dmaengine_debugfs_init() from late_initcall to be called from
  dma_bus_init to avoid races due to probe orders of drivers.
- Separate patch to create DMA driver directories for debugfs

Changes since v3:
- Create a directory for dmaengine and name the initial file as summary
- Function to get the debugfs root for DMA drivers if they want to place files
- Custom dbg_summary_show implementation for k3-udma

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

The basic debugfs file (/sys/kernel/debug/dmaengine/summary) can be used to
query basic information about the DMAengine usage (am654-evm):

# cat /sys/kernel/debug/dmaengine/summary
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

Drivers can implement custom dbg_summary_show to add extended information via
the summary file, like with the second patch for k3-udma (j721e-evm):

# cat /sys/kernel/debug/dmaengine/summary
dma0 (285c0000.dma-controller): number of channels: 24

dma1 (31150000.dma-controller): number of channels: 84
 dma1chan0    | 2b00000.mcasp:tx (MEM_TO_DEV, tchan16 [0x1010 -> 0xc400], PDMA[ ACC32 BURST ], TR mode)
 dma1chan1    | 2b00000.mcasp:rx (DEV_TO_MEM, rchan16 [0x4400 -> 0x9010], PDMA[ ACC32 BURST ], TR mode)
 dma1chan2    | 2ba0000.mcasp:tx (MEM_TO_DEV, tchan17 [0x1011 -> 0xc507], PDMA[ ACC32 BURST ], TR mode)
 dma1chan3    | 2ba0000.mcasp:rx (DEV_TO_MEM, rchan17 [0x4507 -> 0x9011], PDMA[ ACC32 BURST ], TR mode)
 dma1chan4    | in-use (MEM_TO_MEM, chan0 pair [0x1000 -> 0x9000], PSI-L Native, TR mode)
 dma1chan5    | in-use (MEM_TO_MEM, chan1 pair [0x1001 -> 0x9001], PSI-L Native, TR mode)
 dma1chan6    | in-use (MEM_TO_MEM, chan4 pair [0x1004 -> 0x9004], PSI-L Native, TR mode)
 dma1chan7    | in-use (MEM_TO_MEM, chan5 pair [0x1005 -> 0x9005], PSI-L Native, TR mode)

With the last patch the debugfs looks like this:
# ls -al /sys/kernel/debug/dmaengine/
total 0
drwxr-xr-x  4 root root 0 Jan  1 02:00 .
drwx------ 29 root root 0 Jan  1 02:00 ..
drwxr-xr-x  2 root root 0 Jan  1 02:00 285c0000.dma-controller
drwxr-xr-x  2 root root 0 Jan  1 02:00 31150000.dma-controller
-r--r--r--  1 root root 0 Jan  1 02:00 summary


Regards,
Peter
---
Peter Ujfalusi (3):
  dmaengine: Add basic debugfs support
  dmaengine: ti: k3-udma: Implement custom dbg_summary_show for debugfs
  dmaengine: Create debug directories for DMA devices

 drivers/dma/dmaengine.c   | 102 +++++++++++++++++++++++++++++++++++++-
 drivers/dma/dmaengine.h   |  16 ++++++
 drivers/dma/ti/k3-udma.c  |  63 +++++++++++++++++++++++
 include/linux/dmaengine.h |  14 +++++-
 4 files changed, 193 insertions(+), 2 deletions(-)

-- 
Peter

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