From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 Sender: geert.uytterhoeven@gmail.com In-Reply-To: <1519231860.3405.11.camel@pengutronix.de> References: <1518539815-13774-1-git-send-email-geert+renesas@glider.be> <1518539815-13774-3-git-send-email-geert+renesas@glider.be> <1519231860.3405.11.camel@pengutronix.de> From: Geert Uytterhoeven Date: Thu, 22 Feb 2018 09:50:01 +0100 Message-ID: Subject: Re: [PATCH 2/2] vfio: platform: Add generic DT reset support Content-Type: text/plain; charset="UTF-8" To: Philipp Zabel Cc: Geert Uytterhoeven , Baptiste Reynal , Alex Williamson , Rob Herring , Mark Rutland , KVM list , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Linux-Renesas , Linux Kernel Mailing List List-ID: Hi Philipp, On Wed, Feb 21, 2018 at 5:51 PM, Philipp Zabel wrote: > I have a suggestion to avoid having to use the IS_ERR_OR_NULL macro, see > below: > > On Tue, 2018-02-13 at 17:36 +0100, Geert Uytterhoeven wrote: >> Vfio-platform requires reset support, provided either by ACPI, or, on DT >> platforms, by a device-specific reset driver matching against the >> device's compatible value. >> >> On many SoCs, devices are connected to an SoC-internal reset controller, >> and can be reset in a generic way. Hence add support to reset such >> devices using the reset controller subsystem, provided the reset >> hierarchy is described correctly in DT using the "resets" property. >> >> Devices that require a more complex reset procedure can still >> provide a device-specific reset driver, as that takes precedence. >> >> Note that this functionality depends on CONFIG_RESET_CONTROLLER=y, and >> becomes a no-op if reset controller support is disabled. >> >> Signed-off-by: Geert Uytterhoeven >> --- >> drivers/vfio/platform/vfio_platform_common.c | 23 +++++++++++++++++++++-- >> drivers/vfio/platform/vfio_platform_private.h | 1 + >> 2 files changed, 22 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c >> index b60bb5326668498c..5d1e48f96e423508 100644 >> --- a/drivers/vfio/platform/vfio_platform_common.c >> +++ b/drivers/vfio/platform/vfio_platform_common.c >> @@ -17,6 +17,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> #include >> @@ -112,7 +113,13 @@ static bool vfio_platform_has_reset(struct vfio_platform_device *vdev) >> if (VFIO_PLATFORM_IS_ACPI(vdev)) >> return vfio_platform_acpi_has_reset(vdev); >> >> - return vdev->of_reset ? true : false; >> + if (vdev->of_reset) >> + return true; >> + >> + if (!IS_ERR_OR_NULL(vdev->reset_control)) >> + return true; > > I'd avoid storing error values in vdev->reset_control at all, so this > could be: > > if (vdev->reset_control) > return true; Thanks, much better! >> @@ -127,8 +134,15 @@ static int vfio_platform_get_reset(struct vfio_platform_device *vdev) >> vdev->of_reset = vfio_platform_lookup_reset(vdev->compat, >> &vdev->reset_module); >> } >> + if (vdev->of_reset) >> + return 0; >> + >> + vdev->reset_control = __of_reset_control_get(vdev->device->of_node, >> + NULL, 0, false, false); >> + if (!IS_ERR(vdev->reset_control)) >> + return 0; > > if you assign to a local variable first here: > > struct reset_control *rstc; > > ... > > rstc = of_reset_control_get_exclusive(vdev->device->of_node, NULL); > if (!IS_ERR(rstc)) { > vdev->reset_control = rstc; > return 0; > } > > Also, please don't use __of_reset_control_get directly. OK, apparently I didn't read beyond the first #else... >> @@ -217,6 +233,9 @@ static int vfio_platform_call_reset(struct vfio_platform_device *vdev, >> } else if (vdev->of_reset) { >> dev_info(vdev->device, "reset\n"); >> return vdev->of_reset(vdev); >> + } else if (!IS_ERR_OR_NULL(vdev->reset_control)) { >> + dev_info(vdev->device, "reset\n"); >> + return reset_control_reset(vdev->reset_control); > > } else { > if (vdev->reset_control) > dev_info(vdev->device, "reset\n"); > return reset_control_reset(vdev->reset_control); > >> } I'd like to keep the "else if", as that's the pattern used by the blocks above. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds