Re: [PATCH v3 07/38] drm: handle HAS_IOPORT dependencies

Jani Nikula
2023-03-15T11:55:09Z

On Tue, 14 Mar 2023, Niklas Schnelle <schnelle@linux.ibm.com> wrote:
> In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
> not being declared. We thus need to add HAS_IOPORT as dependency for
> those drivers using them. In the bochs driver there is optional MMIO
> support detected at runtime, warn if this isn't taken when
> HAS_IOPORT is not defined.

Not that I care a whole lot, but there should really only be one warning
or even failure to probe at bochs_hw_init() for !bochs->mmio &&
!IS_ENABLED(CONFIG_HAS_IOPORT), not warnings all over the place.

Moreover, the config macro is CONFIG_HAS_IOPORT instead of HAS_IOPORT
that you check for below.

BR,
Jani.

> There is also a direct and hard coded use in cirrus.c which according to
> the comment is only necessary during resume. Let's just skip this as
> for example s390 which doesn't have I/O port support also doesen't
> support suspend/resume.
>
> Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> ---
> drivers/gpu/drm/qxl/Kconfig | 1 +
> drivers/gpu/drm/tiny/bochs.c | 19 +++++++++++++++++++
> drivers/gpu/drm/tiny/cirrus.c | 2 ++
> 3 files changed, 22 insertions(+)
>
> diff --git a/drivers/gpu/drm/qxl/Kconfig b/drivers/gpu/drm/qxl/Kconfig
> index ca3f51c2a8fe..d0e0d440c8d9 100644
> --- a/drivers/gpu/drm/qxl/Kconfig
> +++ b/drivers/gpu/drm/qxl/Kconfig
> @@ -2,6 +2,7 @@
> config DRM_QXL
> tristate "QXL virtual GPU"
> depends on DRM && PCI && MMU
> + depends on HAS_IOPORT
> select DRM_KMS_HELPER
> select DRM_TTM
> select DRM_TTM_HELPER
> diff --git a/drivers/gpu/drm/tiny/bochs.c b/drivers/gpu/drm/tiny/bochs.c
> index 024346054c70..da4a5d53b003 100644
> --- a/drivers/gpu/drm/tiny/bochs.c
> +++ b/drivers/gpu/drm/tiny/bochs.c
> @@ -2,6 +2,7 @@
>
> #include <linux/module.h>
> #include <linux/pci.h>
> +#include <asm/bug.h>
>
> #include <drm/drm_aperture.h>
> #include <drm/drm_atomic_helper.h>
> @@ -105,7 +106,11 @@ static void bochs_vga_writeb(struct bochs_device *bochs, u16 ioport, u8 val)
>
> writeb(val, bochs->mmio + offset);
> } else {
> +#ifdef HAS_IOPORT
> outb(val, ioport);
> +#else
> + WARN_ONCE(1, "Non-MMIO bochs device needs HAS_IOPORT");
> +#endif
> }
> }
>
> @@ -119,7 +124,12 @@ static u8 bochs_vga_readb(struct bochs_device *bochs, u16 ioport)
>
> return readb(bochs->mmio + offset);
> } else {
> +#ifdef HAS_IOPORT
> return inb(ioport);
> +#else
> + WARN_ONCE(1, "Non-MMIO bochs device needs HAS_IOPORT");
> + return 0xff;
> +#endif
> }
> }
>
> @@ -132,8 +142,13 @@ static u16 bochs_dispi_read(struct bochs_device *bochs, u16 reg)
>
> ret = readw(bochs->mmio + offset);
> } else {
> +#ifdef HAS_IOPORT
> outw(reg, VBE_DISPI_IOPORT_INDEX);
> ret = inw(VBE_DISPI_IOPORT_DATA);
> +#else
> + WARN_ONCE(1, "Non-MMIO bochs device needs HAS_IOPORT");
> + ret = 0xffff;
> +#endif
> }
> return ret;
> }
> @@ -145,8 +160,12 @@ static void bochs_dispi_write(struct bochs_device *bochs, u16 reg, u16 val)
>
> writew(val, bochs->mmio + offset);
> } else {
> +#ifdef HAS_IOPORT
> outw(reg, VBE_DISPI_IOPORT_INDEX);
> outw(val, VBE_DISPI_IOPORT_DATA);
> +#else
> + WARN_ONCE(1, "Non-MMIO bochs device needs HAS_IOPORT");
> +#endif
> }
> }
>
> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
> index accfa52e78c5..9da89732c5ac 100644
> --- a/drivers/gpu/drm/tiny/cirrus.c
> +++ b/drivers/gpu/drm/tiny/cirrus.c
> @@ -308,8 +308,10 @@ static int cirrus_mode_set(struct cirrus_device *cirrus,
>
> cirrus_set_start_address(cirrus, 0);
>
> +#ifdef CONFIG_HAS_IOPORT
> /* Unblank (needed on S3 resume, vgabios doesn't do it then) */
> outb(0x20, 0x3c0);
> +#endif
>
> drm_dev_exit(idx);
> return 0;

--
Jani Nikula, Intel Open Source Graphics Center