[igt-dev] [PATCH i-g-t v2] lib/i915: Add a helper to read mmio registers via ioctl

Kamil Konieczny kamil.konieczny at linux.intel.com
Mon Aug 28 11:23:09 UTC 2023


Hi Alan,

On 2023-08-25 at 11:37:59 -0700, Alan Previn wrote:
> Add a helper into existing ioctl_wrappers.c  to call
> DRM_IOCTL_I915_REG_READ to read whitelisted registers.
> 
> v2: - move the new helper into ioctl_wrapper.c/h
>     - follow the ioctl_wrapper convention where __foo
>       is allowed to fail and foo will assert if fails.
>     - use a #define for the RENDER_RING_TIMESTAMP reg.
> 
> Signed-off-by: Alan Previn <alan.previn.teres.alexis at intel.com>
> ---
>  lib/intel_reg.h                      |  3 ++
>  lib/ioctl_wrappers.c                 | 42 ++++++++++++++++++++++++++++
>  lib/ioctl_wrappers.h                 |  2 ++
>  tests/i915/gem_reg_read.c            | 28 ++++---------------
>  tests/i915/i915_pm_rpm.c             | 10 ++++---
>  tools/i915-perf/i915_perf_recorder.c |  9 +++---
>  tools/intel_forcewaked.c             |  4 ++-
>  7 files changed, 66 insertions(+), 32 deletions(-)
> 
> diff --git a/lib/intel_reg.h b/lib/intel_reg.h
> index 3bf3676dc..04ea93eb6 100644
> --- a/lib/intel_reg.h
> +++ b/lib/intel_reg.h
> @@ -689,6 +689,9 @@ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
>  #define GEN12_GFX_AUX_TABLE_BASE_ADDR	0x4200
>  #define GEN12_VEBOX_AUX_TABLE_BASE_ADDR	0x4230
>  
> +/* Command Streamer registers
> + */
> +#define RENDER_RING_TIMESTAMP 0x2358
>  
>  /* BitBlt Instructions
>   *
> diff --git a/lib/ioctl_wrappers.c b/lib/ioctl_wrappers.c
> index 146973f0d..ddaadd673 100644
> --- a/lib/ioctl_wrappers.c
> +++ b/lib/ioctl_wrappers.c
> @@ -887,6 +887,48 @@ bool gem_engine_reset_enabled(int fd)
>  	return gem_gpu_reset_type(fd) > 1;
>  }
>  
> +/**
> + * __i915_reg_read_ioctl:
> + * @drmfd: device file descriptor
> + * @offset: mmio register to read from
> + * @value: ptr to fill with results from read
> + *
> + * This function uses DRM_IOCTL_I915_REG_READ to read the
> + * register and so it can return NOACCES if i915 doesn't allow.
> + *
> + * Returns: This is allowed to fail, with -errno returned.

Please look at other functions, imho better here:

 * Return:
 * 0 if successfull, with *value filled
 * otherwise -errno

> + */
> +int __i915_reg_read_ioctl(int drmfd, __u64 offset, __u64 *value)
> +{
> +	struct drm_i915_reg_read reg_read = {0};
> +	int ret = 0;
> +
> +	reg_read.offset = offset;
> +	if (igt_ioctl(drmfd, DRM_IOCTL_I915_REG_READ, &reg_read))
> +		ret = -errno;
> +	else if (value)
> +		*value = reg_read.val;
> +
> +	return ret;
> +}
> +
> +/**
> + * i915_reg_read_ioctl:
> + * @drmfd: device file descriptor
> + * @offset: mmio register to read from
> + * @value: ptr to fill with results from read
> + *
> + * This function uses DRM_IOCTL_I915_REG_READ to read the
> + * register and so it can return NOACCES if i915 doesn't allow.
-------------- ^^^^^^
Cut description from "and so".

> + * This version will assert if the ioctl fails
> + *
> + */
> +void i915_reg_read_ioctl(int drmfd, __u64 offset, __u64 *value)
-- ^^^^
You may just return __u64 here.

> +{
> +	igt_assert_eq(__i915_reg_read_ioctl(drmfd, offset, value), 0);
> +	errno = 0;
> +}
> +
>  bool gem_has_llc(int fd)
>  {
>  	int has_llc;
> diff --git a/lib/ioctl_wrappers.h b/lib/ioctl_wrappers.h
> index b7d7c2ad9..b37022401 100644
> --- a/lib/ioctl_wrappers.h
> +++ b/lib/ioctl_wrappers.h
> @@ -79,6 +79,8 @@ void gem_execbuf_wr(int fd, struct drm_i915_gem_execbuffer2 *execbuf);
>  int __gem_execbuf_wr(int fd, struct drm_i915_gem_execbuffer2 *execbuf);
>  void gem_execbuf(int fd, struct drm_i915_gem_execbuffer2 *execbuf);
>  int __gem_execbuf(int fd, struct drm_i915_gem_execbuffer2 *execbuf);
> +int __i915_reg_read_ioctl(int drmfd, __u64 offset, __u64 *value);
> +void i915_reg_read_ioctl(int drmfd, __u64 offset, __u64 *value);
>  
>  #ifndef I915_GEM_DOMAIN_WC
>  #define I915_GEM_DOMAIN_WC 0x80
> diff --git a/tests/i915/gem_reg_read.c b/tests/i915/gem_reg_read.c
> index de6788abe..4bf330df6 100644
> --- a/tests/i915/gem_reg_read.c
> +++ b/tests/i915/gem_reg_read.c
> @@ -32,6 +32,8 @@
>  #include <sys/utsname.h>
>  #include <time.h>
>  
> +#include "lib/ioctl_wrappers.h"
> +
>  /**
>   * TEST: gem reg read
>   * Feature: gem_core
> @@ -52,24 +54,6 @@ struct local_drm_i915_reg_read {
>  	__u64 val; /* Return value */
>  };
>  
> -#define REG_READ_IOCTL DRM_IOWR(DRM_COMMAND_BASE + 0x31, struct local_drm_i915_reg_read)
> -
> -#define RENDER_RING_TIMESTAMP 0x2358
> -
> -static int read_register(int fd, uint64_t offset, uint64_t * val)
> -{
> -	int ret = 0;
> -	struct local_drm_i915_reg_read reg_read;
> -	reg_read.offset = offset;
> -
> -	if (drmIoctl(fd, REG_READ_IOCTL, &reg_read))
> -		ret = -errno;
> -
> -	*val = reg_read.val;
> -
> -	return ret;
> -}
> -
>  static bool check_kernel_x86_64(void)
>  {
>  	int ret;
> @@ -87,9 +71,9 @@ static bool check_kernel_x86_64(void)
>  static bool check_timestamp(int fd)
>  {
>  	int ret;
> -	uint64_t val;
> +	__u64 val;
--- ^^^^^
Looks strange, may we left it untouched?

>  
> -	ret = read_register(fd, RENDER_RING_TIMESTAMP | 1, &val);
> +	ret = __i915_reg_read_ioctl(fd, RENDER_RING_TIMESTAMP | 1, &val);
>  
>  	return ret == 0;
>  }
> @@ -103,7 +87,7 @@ static int timer_query(int fd, uint64_t * val)
>  	if (has_proper_timestamp)
>  		offset |= 1;
>  
> -	ret = read_register(fd, offset, val);
> +	ret = __i915_reg_read_ioctl(fd, offset, (__u64 *)val);
>  
>  /*
>   * When reading the timestamp register with single 64b read, we are observing
> @@ -168,7 +152,7 @@ igt_main
>  	}
>  
>  	igt_subtest("bad-register")
> -		igt_assert_eq(read_register(fd, 0x12345678, &val), -EINVAL);
> +		igt_assert_eq(__i915_reg_read_ioctl(fd, 0x12345678, (__u64 *)&val), -EINVAL);
>  
>  	igt_subtest("timestamp-moving") {
>  		igt_skip_on(timer_query(fd, &val) != 0);
> diff --git a/tests/i915/i915_pm_rpm.c b/tests/i915/i915_pm_rpm.c
> index 17413ffe5..4bc1f37a3 100644
> --- a/tests/i915/i915_pm_rpm.c
> +++ b/tests/i915/i915_pm_rpm.c
> @@ -40,6 +40,10 @@
>  #include <sys/mman.h>
>  #include <sys/types.h>
>  #include <sys/stat.h>
> +
> +#include "lib/ioctl_wrappers.h"
> +#include "lib/intel_reg.h"
> +
>  /**
>   * TEST: i915 pm rpm
>   *
> @@ -1852,13 +1856,11 @@ static void gem_evict_pwrite_subtest(void)
>  /* This also triggered WARNs on dmesg at some point. */
>  static void reg_read_ioctl_subtest(void)
>  {
> -	struct drm_i915_reg_read rr = {
> -		.offset = 0x2358, /* render ring timestamp */
> -	};
> +	__u64 val;
>  
>  	disable_all_screens_and_wait(&ms_data);
>  
> -	do_ioctl(drm_fd, DRM_IOCTL_I915_REG_READ, &rr);
> +	i915_reg_read_ioctl(drm_fd, RENDER_RING_TIMESTAMP, &val);
>  
>  	igt_assert(wait_for_suspended());
>  }
> diff --git a/tools/i915-perf/i915_perf_recorder.c b/tools/i915-perf/i915_perf_recorder.c
> index ca4354832..9873fec4c 100644
> --- a/tools/i915-perf/i915_perf_recorder.c
> +++ b/tools/i915-perf/i915_perf_recorder.c
> @@ -44,14 +44,15 @@
>  
>  #include <i915_drm.h>
>  
> -#include "i915/i915_drm_local.h"
> -
> +#include "i915_perf_recorder_commands.h"

Why do you touch unrelated headers?

>  #include "igt_core.h"
>  #include "intel_chipset.h"
> +
> +#include "i915/i915_drm_local.h"
>  #include "i915/perf.h"
>  #include "i915/perf_data.h"
>  
> -#include "i915_perf_recorder_commands.h"
> +#include "lib/intel_reg.h"
------------ ^^^^^^^^^^^^^^^
You need only this here.

Regards,
Kamil

>  
>  #define ALIGN(v, a) (((v) + (a)-1) & ~((a)-1))
>  #define ARRAY_SIZE(arr) (sizeof(arr)/sizeof((arr)[0]))
> @@ -623,8 +624,6 @@ get_correlation_timestamps(struct intel_perf_record_timestamp_correlation *corr,
>  	} attempts[3];
>  	uint32_t best = 0;
>  
> -#define RENDER_RING_TIMESTAMP 0x2358
> -
>          reg_read.offset = RENDER_RING_TIMESTAMP | I915_REG_READ_8B_WA;
>  
>  	/* Gather 3 correlations. */
> diff --git a/tools/intel_forcewaked.c b/tools/intel_forcewaked.c
> index 87b26d43a..584358446 100644
> --- a/tools/intel_forcewaked.c
> +++ b/tools/intel_forcewaked.c
> @@ -38,6 +38,8 @@
>  #include "intel_chipset.h"
>  #include "drmtest.h"
>  
> +#include "lib/intel_reg.h"
> +
>  bool daemonized;
>  
>  #define INFO_PRINT(...) \
> @@ -59,7 +61,7 @@ help(char *prog) {
>  static int
>  is_alive(struct intel_mmio_data *mmio_data) {
>  	/* Read the timestamp, which should *almost* always be !0 */
> -	return (intel_register_read(mmio_data, 0x2358) != 0);
> +	return (intel_register_read(mmio_data, RENDER_RING_TIMESTAMP) != 0);
>  }
>  
>  int main(int argc, char *argv[])
> -- 
> 2.39.0
> 


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