[PATCH] drm/amdgpu: replace mutex with spin_lock

[S, Shirish]

On 5/30/2018 9:10 PM, Christian König wrote:
> Keep in mind that under SRIOV you can read registers while in atomic 
> context, e.g. while holding a spinlock.
>
> Please double check if that won't bite us.
>
> Apart from that the change looks good to me,
Thanks Christian, i verified boot, s3, s5 on Stoney with this patch.
Have re-spun V2 which has the exact trace in which scenario this BUG is hit.
Regards,
Shirish S
> Christian.
>
> Am 30.05.2018 um 12:19 schrieb Shirish S:
>> mutex's lead to sleeps which should be avoided in
>> atomic context.
>> Hence this patch replaces it with the spin_locks.
>>
>> Signed-off-by: Shirish S <shirish.s at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c | 2 +-
>>   drivers/gpu/drm/amd/amdgpu/atom.c            | 4 ++--
>>   drivers/gpu/drm/amd/amdgpu/atom.h            | 3 ++-
>>   3 files changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
>> index bf872f6..ba3d4b9 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_atombios.c
>> @@ -2033,7 +2033,7 @@ int amdgpu_atombios_init(struct amdgpu_device 
>> *adev)
>>           return -ENOMEM;
>>       }
>>   - mutex_init(&adev->mode_info.atom_context->mutex);
>> + spin_lock_init(&adev->mode_info.atom_context->lock);
>>       if (adev->is_atom_fw) {
>>           amdgpu_atomfirmware_scratch_regs_init(adev);
>>           amdgpu_atomfirmware_allocate_fb_scratch(adev);
>> diff --git a/drivers/gpu/drm/amd/amdgpu/atom.c 
>> b/drivers/gpu/drm/amd/amdgpu/atom.c
>> index 69500a8..bfd98f0 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/atom.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/atom.c
>> @@ -1261,7 +1261,7 @@ int amdgpu_atom_execute_table(struct 
>> atom_context *ctx, int index, uint32_t * pa
>>   {
>>       int r;
>>   -    mutex_lock(&ctx->mutex);
>> +    spin_lock(&ctx->lock);
>>       /* reset data block */
>>       ctx->data_block = 0;
>>       /* reset reg block */
>> @@ -1274,7 +1274,7 @@ int amdgpu_atom_execute_table(struct 
>> atom_context *ctx, int index, uint32_t * pa
>>       ctx->divmul[0] = 0;
>>       ctx->divmul[1] = 0;
>>       r = amdgpu_atom_execute_table_locked(ctx, index, params);
>> -    mutex_unlock(&ctx->mutex);
>> +    spin_unlock(&ctx->lock);
>>       return r;
>>   }
>>   diff --git a/drivers/gpu/drm/amd/amdgpu/atom.h 
>> b/drivers/gpu/drm/amd/amdgpu/atom.h
>> index a391709..cdfb0d0 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/atom.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/atom.h
>> @@ -26,6 +26,7 @@
>>   #define ATOM_H
>>     #include <linux/types.h>
>> +#include <linux/spinlock_types.h>
>>   #include <drm/drmP.h>
>>     #define ATOM_BIOS_MAGIC        0xAA55
>> @@ -125,7 +126,7 @@ struct card_info {
>>     struct atom_context {
>>       struct card_info *card;
>> -    struct mutex mutex;
>> +    spinlock_t lock;
>>       void *bios;
>>       uint32_t cmd_table, data_table;
>>       uint16_t *iio;
>

-- 
Regards,
Shirish S