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SubjectRE: dmaengine : xilinx_dma two issues
Date
> -----Original Message-----
> From: Paul Thomas <pthomas8589@gmail.com>
> Sent: Monday, December 28, 2020 10:14 AM
> To: Dan Williams <dan.j.williams@intel.com>; Vinod Koul
> <vkoul@kernel.org>; Michal Simek <michals@xilinx.com>; Radhey Shyam
> Pandey <radheys@xilinx.com>; Matthew Murrian
> <matthew.murrian@goctsi.com>; Romain Perier
> <romain.perier@gmail.com>; Krzysztof Kozlowski <krzk@kernel.org>; Marc
> Ferland <ferlandm@amotus.ca>; Sebastian von Ohr
> <vonohr@smaract.com>; dmaengine@vger.kernel.org; Linux ARM <linux-
> arm-kernel@lists.infradead.org>; linux-kernel <linux-
> kernel@vger.kernel.org>
> Subject: dmaengine : xilinx_dma two issues
>
> Hello,
>
> I'm trying to get the 5.10 kernel up and running for our system, and I'm
> running into a couple of issues with xilinx_dma.
+ (Xilinx mailing list)

Thanks for bringing the issues to our notice. Replies inline.

>
> First, commit 14ccf0aab46e 'dmaengine: xilinx_dma: In dma channel probe
> fix node order dependency' breaks our usage. Before this commit a call to:
> dma_request_chan(&indio_dev->dev, "axi_dma_0"); returns fine, but after
> that commit it returns -19. The reason for this seems to be that the only
> channel that is setup is channel 1 (chan->id is 1 in xilinx_dma_chan_probe()).
> However in
> of_dma_xilinx_xlate() chan_id is gets set to 0 (int chan_id = dma_spec-
> >args[0];), which causes the:
> !xdev->chan[chan_id]
> test to fail in of_dma_xilinx_xlate()

What is the channel number passed in
dmaclient DT?

dmas = <& axi_dma_0 1>
dma-names = "axi_dma_0"

>
> Our device-tree entry looks like this:
> axi_dma_0: dma@80002000 {
> status = "okay";
> #dma-cells = <1>;
> compatible = "xlnx,axi-dma-1.00.a";
> interrupt-parent = <&gic>;
> interrupts = <0 89 4>;
> reg = <0x0 0x80002000 0x0 0x1000>;
> xlnx,addrwidth = <0x20>;
> clocks = <&zynqmp_clk LPD_LSBUS>, <&zynqmp_clk LPD_LSBUS>,
> <&zynqmp_clk LPD_LSBUS>, <&zynqmp_clk LPD_LSBUS>;
> clock-names = "s_axi_lite_aclk", "m_axi_sg_aclk", "m_axi_mm2s_aclk",
> "m_axi_s2mm_aclk";
> dma-channel@80002030 {
> compatible = "xlnx,axi-dma-s2mm-channel";
> dma-channels = <0x1>;
> interrupts = <0 89 4>;
> xlnx,datawidth = <0x20>;
> xlnx,device-id = <0x0>;
> };
> };
>
> This is on a 5.10.1 kernel on arm64 zynqmp hardware.
>
> The second issue goes a little further back to commit e81274cd6b526
> 'dmaengine: add support to dynamic register/unregister of channels'.
> After this commit even just removing the module 'rmmod xilinx_dma',
> without ever using it, results in a kernel oops like this:
> [ 37.214568] xilinx-vdma 80002000.dma: ch 0: SG disabled
> [ 37.219807] xilinx-vdma 80002000.dma: WARN: Device release is not
> defined so it is not safe to unbind this driver while in use
> [ 37.231299] xilinx-vdma 80002000.dma: Xilinx AXI DMA Engine Driver
> Probed!!
> [ 42.100660] Unable to handle kernel paging request at virtual
> address dead000000000108
> [ 42.108598] Mem abort info:
> [ 42.111393] ESR = 0x96000044
> [ 42.114443] EC = 0x25: DABT (current EL), IL = 32 bits
> [ 42.119744] SET = 0, FnV = 0
> [ 42.122794] EA = 0, S1PTW = 0
> [ 42.125918] Data abort info:
> [ 42.128789] ISV = 0, ISS = 0x00000044
> [ 42.132617] CM = 0, WnR = 1
> [ 42.135577] [dead000000000108] address between user and kernel
> address ranges
> [ 42.142705] Internal error: Oops: 96000044 [#1] SMP
> [ 42.147566] Modules linked in: xilinx_dma(-) clk_xlnx_clock_wizard
> uio_pdrv_genirq
> [ 42.155139] CPU: 1 PID: 2075 Comm: rmmod Not tainted
> 5.10.1-00026-g3a2e6dd7a05-dirty #192
> [ 42.163302] Hardware name: Enclustra XU5 SOM (DT)
> [ 42.167992] pstate: 40000005 (nZcv daif -PAN -UAO -TCO BTYPE=--)
> [ 42.173996] pc : xilinx_dma_chan_remove+0x74/0xa0 [xilinx_dma]
> [ 42.179815] lr : xilinx_dma_chan_remove+0x70/0xa0 [xilinx_dma]
> [ 42.185636] sp : ffffffc01112bca0
> [ 42.188935] x29: ffffffc01112bca0 x28: ffffff80402ea640
> [ 42.194238] x27: 0000000000000000 x26: 0000000000000000
> [ 42.199542] x25: 0000000000000000 x24: 0000000000000000
> [ 42.204845] x23: 0000000000000000 x22: 0000000000000000
> [ 42.210149] x21: ffffffc0088a2028 x20: ffffff8040c08410
> [ 42.215452] x19: ffffff80423fa480 x18: ffffffffffffffff
> [ 42.220756] x17: 0000000000000000 x16: 0000000000000000
> [ 42.226059] x15: ffffffc010ce88c8 x14: 0000000000000040
> [ 42.231363] x13: ffffff0000000000 x12: ffffffffffffffff
> [ 42.236667] x11: 0000000000000028 x10: ffffffff7fffffff
> [ 42.241970] x9 : ffffffff00f0dfe0 x8 : 0000000000000000
> [ 42.247273] x7 : ffffffc010da4000 x6 : 0000000000000000
> [ 42.252577] x5 : 0000000000210d00 x4 : ffffffc010da4da0
> [ 42.257881] x3 : ffffff80423fa578 x2 : 0000000000000000
> [ 42.263184] x1 : dead000000000100 x0 : dead000000000122
> [ 42.268488] Call trace:
> [ 42.270923] xilinx_dma_chan_remove+0x74/0xa0 [xilinx_dma]
> [ 42.276399] xilinx_dma_remove+0x3c/0x70 [xilinx_dma]
> [ 42.281446] platform_drv_remove+0x24/0x38
> [ 42.285530] device_release_driver_internal+0xec/0x1a8
> [ 42.290659] driver_detach+0x64/0xd8
> [ 42.294226] bus_remove_driver+0x58/0xb8
> [ 42.298133] driver_unregister+0x30/0x60
> [ 42.302048] platform_driver_unregister+0x14/0x20
> [ 42.306744] xilinx_vdma_driver_exit+0x18/0x978 [xilinx_dma]
> [ 42.312396] __arm64_sys_delete_module+0x1e4/0x270
> [ 42.317178] el0_svc_common.constprop.4+0x68/0x170
> [ 42.321959] do_el0_svc+0x70/0x90
> [ 42.325267] el0_svc+0x14/0x20
> [ 42.328313] el0_sync_handler+0x90/0xb8
> [ 42.332141] el0_sync+0x158/0x180
> [ 42.335442] Code: 95dfce29 9103c260 95de7ffb a9490261 (f9000420)
> [ 42.341525] ---[ end trace dbd90aeb5ca71943 ]---
>
> So if I use the 04c2bc2bede1 (commit before 14ccf0aab46e) version of
> xilinx_dma.c and never remove the module then it is working with the
> 5.10.1 kernel.

Ok, we will analyze this issue and report back the findings.

>
> Hopefully, this will be clear to someone how these issues can be resolved. In
> general we've been very happy using the xilinx dma.
>
> I'm not subscribed to the linux-kernel ML so if you need any further info or
> testing just keep me in the to: list.
>
> thanks,
> Paul
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