On Wed, May 28, 2014 at 12:05 PM, Shawn Guo <shawn.guo@xxxxxxxxxxxxx> wrote: > Doing suspend/resume on imx6q and imx53 boards with no SATA disk > attached will trigger the following warning. > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 661 at drivers/ata/libahci.c:224 ahci_enable_ahci+0x74/0x8) > Modules linked in: > CPU: 0 PID: 661 Comm: sh Tainted: G W 3.15.0-rc5-next-20140521-000027 > Backtrace: > [<80011c90>] (dump_backtrace) from [<80011e2c>] (show_stack+0x18/0x1c) > r6:803a22f4 r5:00000000 r4:00000000 r3:00000000 > [<80011e14>] (show_stack) from [<80661e60>] (dump_stack+0x88/0xa4) > [<80661dd8>] (dump_stack) from [<80028fdc>] (warn_slowpath_common+0x70/0x94) > r5:00000009 r4:00000000 > [<80028f6c>] (warn_slowpath_common) from [<80029024>] (warn_slowpath_null+0x24/) > r8:808f68c4 r7:00000000 r6:00000000 r5:00000000 r4:e0810004 > [<80029000>] (warn_slowpath_null) from [<803a22f4>] (ahci_enable_ahci+0x74/0x80) > [<803a2280>] (ahci_enable_ahci) from [<803a2324>] (ahci_reset_controller+0x24/0) > r8:ddcd9410 r7:80351178 r6:ddcd9444 r5:dde8b850 r4:e0810000 r3:ddf35e90 > [<803a2300>] (ahci_reset_controller) from [<803a2c68>] (ahci_platform_resume_ho) > r7:80351178 r6:ddcd9444 r5:dde8b850 r4:ddcd9410 > [<803a2c30>] (ahci_platform_resume_host) from [<803a38f0>] (imx_ahci_resume+0x2) > r5:00000000 r4:ddcd9410 > [<803a38c4>] (imx_ahci_resume) from [<803511ac>] (platform_pm_resume+0x34/0x54) > .... > > The reason is that the SATA controller has no working clock at this > point, and thus ahci_enable_ahci() fails to enable the controller. In > case that there is no SATA disk attached, the imx_sata_disable() gets > called in ahci_imx_error_handler(), and both sata_clk and sata_ref_clk > will be disabled there. Because all the imx_sata_enable() calls > afterward will return immediately due to imxpriv->no_device check, the > SATA controller working clock sata_clk will never get any chance to be > enabled again. > > This is a regression caused by commit 90870d79d4f2 (ahci-imx: Port to > library-ised ahci_platform). Before the commit, only sata_ref_clk is > managed by the driver in enable/disable function. But after the commit, > all the clocks are enabled/disabled in a row by ahci platform helpers > ahci_platform_enable[disable]_clks. Since ahb_clk is a bus clock which > does not have gate at all, and i.MX low-power hardware module already > manages sata_clk across suspend/resume cycle, the only clock that needs > to be managed by software is sata_ref_clk. > > So instead of using ahci_platform_enable[disable]_clks to manage all > the clocks in a row from imx_sata_enable[disable], we should manage > only sata_ref_clk in there. > > Reported-by: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx> > Fixes: 90870d79d4f2 (ahci-imx: Port to library-ised ahci_platform) > Signed-off-by: Shawn Guo <shawn.guo@xxxxxxxxxxxxx> Tested-by: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
