On Fri, 29 Mar 2019, Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx> wrote:
> On 29/03/2019 09:54, Jani Nikula wrote:
>> On Wed, 27 Mar 2019, Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx> wrote:
>>> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
>>>
>>> Concept of a sub-platform already exist in our code (like ULX and ULT
>>> platform variants and similar),implemented via the macros which check a
>>> list of device ids to determine a match.
>>>
>>> With this patch we consolidate device ids checking into a single function
>>> called during early driver load.
>>>
>>> A few low bits in the platform mask are reserved for sub-platform
>>> identification and defined as a per-platform namespace.
>>>
>>> At the same time it future proofs the platform_mask handling by preparing
>>> the code for easy extending, and tidies the very verbose WARN strings
>>> generated when IS_PLATFORM macros are embedded into a WARN type
>>> statements.
>>>
>>> v2: Fixed IS_SUBPLATFORM. Updated commit msg.
>>> v3: Chris was right, there is an ordering problem.
>>>
>>> v4:
>>> * Catch-up with new sub-platforms.
>>> * Rebase for RUNTIME_INFO.
>>> * Drop subplatform mask union tricks and convert platform_mask to an
>>> array for extensibility.
>>>
>>> v5:
>>> * Fix subplatform check.
>>> * Protect against forgetting to expand subplatform bits.
>>> * Remove platform enum tallying.
>>> * Add subplatform to error state. (Chris)
>>> * Drop macros and just use static inlines.
>>> * Remove redundant IRONLAKE_M. (Ville)
>>>
>>> v6:
>>> * Split out Ironlake change.
>>> * Optimize subplatform check.
>>> * Use __always_inline. (Lucas)
>>> * Add platform_mask comment. (Paulo)
>>> * Pass stored runtime info in error capture. (Chris)
>>>
>>> v7:
>>> * Rebased for new AML ULX device id.
>>> * Bump platform mask array size for EHL.
>>> * Stop mentioning device ids in intel_device_subplatform_init by using
>>> the trick of splitting macros i915_pciids.h. (Jani)
>>> * AML seems to be either a subplatform of KBL or CFL so express it like
>>> that.
>>>
>>> v8:
>>> * Use one device id table per subplatform. (Jani)
>>>
>>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
>>> Suggested-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
>>> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
>>> Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
>>> Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
>>> Cc: Jose Souza <jose.souza@xxxxxxxxx>
>>> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>>> Cc: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
>>> Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> # v6
>>> ---
>>> drivers/gpu/drm/i915/i915_drv.c | 8 +-
>>> drivers/gpu/drm/i915/i915_drv.h | 123 ++++++++++++++++-------
>>> drivers/gpu/drm/i915/i915_gpu_error.c | 3 +
>>> drivers/gpu/drm/i915/i915_pci.c | 2 +-
>>> drivers/gpu/drm/i915/intel_device_info.c | 93 +++++++++++++++++
>>> drivers/gpu/drm/i915/intel_device_info.h | 27 ++++-
>>> 6 files changed, 214 insertions(+), 42 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
>>> index f1334f5d4ead..74734d7661e5 100644
>>> --- a/drivers/gpu/drm/i915/i915_drv.c
>>> +++ b/drivers/gpu/drm/i915/i915_drv.c
>>> @@ -868,6 +868,8 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv)
>>> if (i915_inject_load_failure())
>>> return -ENODEV;
>>>
>>> + intel_device_info_subplatform_init(dev_priv);
>>> +
>>> spin_lock_init(&dev_priv->irq_lock);
>>> spin_lock_init(&dev_priv->gpu_error.lock);
>>> mutex_init(&dev_priv->backlight_lock);
>>> @@ -1718,10 +1720,12 @@ static void i915_welcome_messages(struct drm_i915_private *dev_priv)
>>> if (drm_debug & DRM_UT_DRIVER) {
>>> struct drm_printer p = drm_debug_printer("i915 device info:");
>>>
>>> - drm_printf(&p, "pciid=0x%04x rev=0x%02x platform=%s gen=%i\n",
>>> + drm_printf(&p, "pciid=0x%04x rev=0x%02x platform=%s (subplatform=0x%x) gen=%i\n",
>>> INTEL_DEVID(dev_priv),
>>> INTEL_REVID(dev_priv),
>>> intel_platform_name(INTEL_INFO(dev_priv)->platform),
>>> + intel_subplatform(RUNTIME_INFO(dev_priv),
>>> + INTEL_INFO(dev_priv)->platform),
>>> INTEL_GEN(dev_priv));
>>>
>>> intel_device_info_dump_flags(INTEL_INFO(dev_priv), &p);
>>> @@ -1764,8 +1768,6 @@ i915_driver_create(struct pci_dev *pdev, const struct pci_device_id *ent)
>>> memcpy(device_info, match_info, sizeof(*device_info));
>>> RUNTIME_INFO(i915)->device_id = pdev->device;
>>>
>>> - BUILD_BUG_ON(INTEL_MAX_PLATFORMS >
>>> - BITS_PER_TYPE(device_info->platform_mask));
>>> BUG_ON(device_info->gen > BITS_PER_TYPE(device_info->gen_mask));
>>>
>>> return i915;
>>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>>> index 9d3cab9406e1..b7d3f3a45ed9 100644
>>> --- a/drivers/gpu/drm/i915/i915_drv.h
>>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>>> @@ -2298,7 +2298,67 @@ static inline unsigned int i915_sg_segment_size(void)
>>> #define IS_REVID(p, since, until) \
>>> (INTEL_REVID(p) >= (since) && INTEL_REVID(p) <= (until))
>>>
>>> -#define IS_PLATFORM(dev_priv, p) (INTEL_INFO(dev_priv)->platform_mask & BIT(p))
>>> +static __always_inline unsigned int
>>> +__platform_mask_index(const struct intel_runtime_info *info,
>>> + enum intel_platform p)
>>> +{
>>> + const unsigned int pbits =
>>> + BITS_PER_TYPE(info->platform_mask[0]) - INTEL_SUBPLATFORM_BITS;
>>> +
>>> + /* Expand the platform_mask array if this fails. */
>>> + BUILD_BUG_ON(INTEL_MAX_PLATFORMS >
>>> + pbits * ARRAY_SIZE(info->platform_mask));
>>> +
>>> + return p / pbits;
>>> +}
>>> +
>>> +static __always_inline unsigned int
>>> +__platform_mask_bit(const struct intel_runtime_info *info,
>>> + enum intel_platform p)
>>> +{
>>> + const unsigned int pbits =
>>> + BITS_PER_TYPE(info->platform_mask[0]) - INTEL_SUBPLATFORM_BITS;
>>> +
>>> + return p % pbits + INTEL_SUBPLATFORM_BITS;
>>> +}
>>> +
>>> +static inline u32
>>> +intel_subplatform(const struct intel_runtime_info *info, enum intel_platform p)
>>> +{
>>> + const unsigned int pi = __platform_mask_index(info, p);
>>> +
>>> + return info->platform_mask[pi] & INTEL_SUBPLATFORM_BITS;
>>> +}
>>> +
>>> +static __always_inline bool
>>> +IS_PLATFORM(const struct drm_i915_private *i915, enum intel_platform p)
>>> +{
>>> + const struct intel_runtime_info *info = RUNTIME_INFO(i915);
>>> + const unsigned int pi = __platform_mask_index(info, p);
>>> + const unsigned int pb = __platform_mask_bit(info, p);
>>> +
>>> + BUILD_BUG_ON(!__builtin_constant_p(p));
>>> +
>>> + return info->platform_mask[pi] & BIT(pb);
>>> +}
>>> +
>>> +static __always_inline bool
>>> +IS_SUBPLATFORM(const struct drm_i915_private *i915,
>>> + enum intel_platform p, unsigned int s)
>>> +{
>>> + const struct intel_runtime_info *info = RUNTIME_INFO(i915);
>>> + const unsigned int pi = __platform_mask_index(info, p);
>>> + const unsigned int pb = __platform_mask_bit(info, p);
>>> + const unsigned int msb = BITS_PER_TYPE(info->platform_mask[0]) - 1;
>>> + const u32 mask = info->platform_mask[pi];
>>> +
>>> + BUILD_BUG_ON(!__builtin_constant_p(p));
>>> + BUILD_BUG_ON(!__builtin_constant_p(s));
>>> + BUILD_BUG_ON((s) >= INTEL_SUBPLATFORM_BITS);
>>> +
>>> + /* Shift and test on the MSB position so sign flag can be used. */
>>> + return ((mask << (msb - pb)) & (mask << (msb - s))) & BIT(msb);
>>> +}
>>
>> Hum, I wonder if the __builtin_constant_p()'s in an inline function are
>> going to be a problem for clang.
>
> No idea.. has something been happening along these lines in the past?
The thread and two patches starting from [1] may be related.
[1] http://mid.mail-archive.com/20181016122938.18757-1-jani.nikula@xxxxxxxxx
> It could be a macro but then all WARN_ON's which use IS_PLATFORM expand
> to most unreadable mess.
I know.
>>> +static bool find_devid(u16 id, const u16 *p, unsigned int num)
>>> +{
>>> + for (; num; num--, p++) {
>>> + if (*p == id)
>>> + return true;
>>> + }
>>
>> Why such a convoluted way of doing what's supposed to be a simple thing?
>> I had to stop at that and wonder what's going on. While this would've
>> been obvious and reviewed with a 2-second glance:
>>
>> int i;
>>
>> for (i = 0; i < num; i++)
>> if (id == p[i])
>> return true;
>>
>> The alternative is zero-terminating the arrays:
>>
>> for (; *p; p++)
>> if (id == *p)
>> return true;
>>
>
> I think mine is not that complicated. It's a standard countdown pattern,
> no? Why add locals or null termination if not needed.
I just like to simplify the code for the humans, not for the compiler.
BR,
Jani.
--
Jani Nikula, Intel Open Source Graphics Center
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