Commits
Shawn Guo committed e6dd42a917e
ahci: imx: manage only sata_ref_clk in imx_sata_enable[disable] 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@freescale.com> Fixes: 90870d79d4f2 (ahci-imx: Port to library-ised ahci_platform) Signed-off-by: Shawn Guo <shawn.guo@freescale.com> Acked-by: Hans de Goede <hdegoede@redhat.com>