netdev - Re: [PATCH V3] net: stmmac: socfpga: Remove re-registration of reset controller

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Date:	Thu, 21 Apr 2016 09:39:56 -0500
From:	Dinh Nguyen <dinguyen@...nsource.altera.com>
To:	Marek Vasut <marex@...x.de>, <netdev@...r.kernel.org>
CC:	<peppe.cavallaro@...com>, <alexandre.torgue@...com>,
	Matthew Gerlach <mgerlach@...nsource.altera.com>,
	"David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH V3] net: stmmac: socfpga: Remove re-registration of reset
 controller



On 04/21/2016 07:11 AM, Marek Vasut wrote:
> Both socfpga_dwmac_parse_data() in dwmac-socfpga.c and stmmac_dvr_probe()
> in stmmac_main.c functions call devm_reset_control_get() to register an
> reset controller for the stmmac. This results in an attempt to register
> two reset controllers for the same non-shared reset line.
> 
> The first attempt to register the reset controller works fine. The second
> attempt fails with warning from the reset controller core, see below.
> The warning is produced because the reset line is non-shared and thus
> it is allowed to have only up-to one reset controller associated with
> that reset line, not two or more.
> 
> The solution has multiple parts. First, the original socfpga_dwmac_init()
> is tweaked to use reset controller pointer from the stmmac_priv (private
> data of the stmmac core) instead of the local instance, which was used
> before. The local re-registration of the reset controller is removed.
> 
> Next, the socfpga_dwmac_init() is moved after stmmac_dvr_probe() in the
> probe function. This order is legal according to Altera and it makes the
> code much easier, since there is no need to temporarily register and
> unregister the reset controller ; the reset controller is already registered
> by the stmmac_dvr_probe().
> 
> Finally, plat_dat->exit and socfpga_dwmac_exit() is no longer necessary,
> since the functionality is already performed by the stmmac core.
> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at drivers/reset/core.c:187 __of_reset_control_get+0x218/0x270
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.6.0-rc4-next-20160419-00015-gabb2477-dirty #4
> Hardware name: Altera SOCFPGA
> [<c010f290>] (unwind_backtrace) from [<c010b82c>] (show_stack+0x10/0x14)
> [<c010b82c>] (show_stack) from [<c0373da4>] (dump_stack+0x94/0xa8)
> [<c0373da4>] (dump_stack) from [<c011bcc0>] (__warn+0xec/0x104)
> [<c011bcc0>] (__warn) from [<c011bd88>] (warn_slowpath_null+0x20/0x28)
> [<c011bd88>] (warn_slowpath_null) from [<c03a6eb4>] (__of_reset_control_get+0x218/0x270)
> [<c03a6eb4>] (__of_reset_control_get) from [<c03a701c>] (__devm_reset_control_get+0x54/0x90)
> [<c03a701c>] (__devm_reset_control_get) from [<c041fa30>] (stmmac_dvr_probe+0x1b4/0x8e8)
> [<c041fa30>] (stmmac_dvr_probe) from [<c04298c8>] (socfpga_dwmac_probe+0x1b8/0x28c)
> [<c04298c8>] (socfpga_dwmac_probe) from [<c03d6ffc>] (platform_drv_probe+0x4c/0xb0)
> [<c03d6ffc>] (platform_drv_probe) from [<c03d54ec>] (driver_probe_device+0x224/0x2bc)
> [<c03d54ec>] (driver_probe_device) from [<c03d5630>] (__driver_attach+0xac/0xb0)
> [<c03d5630>] (__driver_attach) from [<c03d382c>] (bus_for_each_dev+0x6c/0xa0)
> [<c03d382c>] (bus_for_each_dev) from [<c03d4ad4>] (bus_add_driver+0x1a4/0x21c)
> [<c03d4ad4>] (bus_add_driver) from [<c03d60ac>] (driver_register+0x78/0xf8)
> [<c03d60ac>] (driver_register) from [<c0101760>] (do_one_initcall+0x40/0x170)
> [<c0101760>] (do_one_initcall) from [<c0800e38>] (kernel_init_freeable+0x1dc/0x27c)
> [<c0800e38>] (kernel_init_freeable) from [<c05d1bd4>] (kernel_init+0x8/0x114)
> [<c05d1bd4>] (kernel_init) from [<c01076f8>] (ret_from_fork+0x14/0x3c)
> ---[ end trace 059d2fbe87608fa9 ]---
> 
> Signed-off-by: Marek Vasut <marex@...x.de>
> Cc: Matthew Gerlach <mgerlach@...nsource.altera.com>
> Cc: Dinh Nguyen <dinguyen@...nsource.altera.com>
> Cc: David S. Miller <davem@...emloft.net>
> ---
> V2: Add missing stmmac_rst = NULL; into socfpga_dwmac_init_probe()
> V3: Greatly simplify the code by moving socfpga_dwmac_init() after
>     stmmac_dvr_probe(), which is legal. This removes the need for
>     temporary registration of the reset controller, which is super.
>

Tested-by: Dinh Nguyen <dinguyen@...nsource.altera.com>

Thanks,
Dinh