[PATCH libdrm] amdgpu: dynamically detect number of drm devices

[Christian König]

Am 19.04.2018 um 15:06 schrieb xiyuan:
> Hi Christian,
>
> The problem I encountered is that amdgpu_test throws segment fault on 
> a platform with 1 iGPU + 4 dGPU. The root cause is that 'drm_count' 
> returned by drmGetDevices() is 5 which exceeds MAX_CARDS_SUPPORTED, so 
> I decided to make it more flexible to get the actual number of drm 
> devices.
>
> Setting MAX_CARDS_SUPPORTED to 128 is fine to solve my problem but is 
> it a bit large for traversal?

No, not really. MAX_CARDS_SUPPORTED only affects the size of drm_amdgpu 
array. And so we would use 128*4=512 bytes at most.

128 is the maximum the kernel can support at the moment, so that should 
work for a while.

Christian.

>
> Regards,
> Xiaojie
>
>
> On 04/19/2018 07:06 PM, Christian König wrote:
>> Wouldn't it be simpler to just set MAX_CARDS_SUPPORTED to 128?
>>
>> Regards,
>> Christian.
>>
>> Am 19.04.2018 um 12:12 schrieb Xiaojie Yuan:
>>> Change-Id: I36764951bebbcbf06cf84dd43ee946a34ec7b100
>>> Signed-off-by: Xiaojie Yuan <Xiaojie.Yuan at amd.com>
>>> ---
>>>   tests/amdgpu/amdgpu_test.c | 44 
>>> ++++++++++++++++++++++++++++----------
>>>   tests/amdgpu/amdgpu_test.h |  7 +-----
>>>   2 files changed, 34 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/tests/amdgpu/amdgpu_test.c b/tests/amdgpu/amdgpu_test.c
>>> index 96fcd687..f7ac4ab4 100644
>>> --- a/tests/amdgpu/amdgpu_test.c
>>> +++ b/tests/amdgpu/amdgpu_test.c
>>> @@ -61,7 +61,8 @@
>>>    *  Open handles for amdgpu devices
>>>    *
>>>    */
>>> -int drm_amdgpu[MAX_CARDS_SUPPORTED];
>>> +int *drm_amdgpu;
>>> +size_t num_drm_devices;
>>>     /** Open render node to test */
>>>   int open_render_node = 0;    /* By default run most tests on 
>>> primary node */
>>> @@ -238,16 +239,16 @@ static const char options[]   = "hlrps:t:b:d:f";
>>>    */
>>>   static int amdgpu_open_devices(int open_render_node)
>>>   {
>>> -    drmDevicePtr devices[MAX_CARDS_SUPPORTED];
>>> +    drmDevicePtr *devices;
>>>       int i;
>>>       int drm_node;
>>>       int amd_index = 0;
>>>       int drm_count;
>>> +    int drm_count2;
>>>       int fd;
>>>       drmVersionPtr version;
>>>   -    drm_count = drmGetDevices2(0, devices, MAX_CARDS_SUPPORTED);
>>> -
>>> +    drm_count = drmGetDevices2(0, NULL, 0);
>>>       if (drm_count < 0) {
>>>           fprintf(stderr,
>>>               "drmGetDevices2() returned an error %d\n",
>>> @@ -255,6 +256,27 @@ static int amdgpu_open_devices(int 
>>> open_render_node)
>>>           return 0;
>>>       }
>>>   +    devices = calloc(drm_count, sizeof(drmDevicePtr));
>>> +    if (!devices) {
>>> +        goto end;
>>> +    }
>>> +
>>> +    drm_amdgpu = calloc(drm_count, sizeof(int));
>>> +    if (!drm_amdgpu) {
>>> +        goto end;
>>> +    }
>>> +
>>> +    for (i = 0; i < drm_count; i++)
>>> +        drm_amdgpu[i] = -1;
>>> +
>>> +    drm_count2 = drmGetDevices2(0, devices, drm_count);
>>> +    if (drm_count2 != drm_count) {
>>> +        fprintf(stderr, "number of drm devices changed");
>>> +        goto end;
>>> +    }
>>> +
>>> +    num_drm_devices = drm_count;
>>> +
>>>       for (i = 0; i < drm_count; i++) {
>>>           /* If this is not PCI device, skip*/
>>>           if (devices[i]->bustype != DRM_BUS_PCI)
>>> @@ -302,7 +324,9 @@ static int amdgpu_open_devices(int 
>>> open_render_node)
>>>           amd_index++;
>>>       }
>>>   +end:
>>>       drmFreeDevices(devices, drm_count);
>>> +    free(devices);
>>>       return amd_index;
>>>   }
>>>   @@ -311,9 +335,11 @@ static int amdgpu_open_devices(int 
>>> open_render_node)
>>>   static void amdgpu_close_devices()
>>>   {
>>>       int i;
>>> -    for (i = 0; i < MAX_CARDS_SUPPORTED; i++)
>>> +    for (i = 0; i < num_drm_devices; i++)
>>>           if (drm_amdgpu[i] >=0)
>>>               close(drm_amdgpu[i]);
>>> +
>>> +    free(drm_amdgpu);
>>>   }
>>>     /* Print AMD devices information */
>>> @@ -339,7 +365,7 @@ static void amdgpu_print_devices()
>>>         /* Display information of AMD devices */
>>>       printf("Devices:\n");
>>> -    for (i = 0; i < MAX_CARDS_SUPPORTED && drm_amdgpu[i] >=0; i++)
>>> +    for (i = 0; i < num_drm_devices && drm_amdgpu[i] >=0; i++)
>>>           if (drmGetDevice2(drm_amdgpu[i],
>>>               DRM_DEVICE_GET_PCI_REVISION,
>>>               &device) == 0) {
>>> @@ -377,7 +403,7 @@ static int amdgpu_find_device(uint8_t bus, 
>>> uint16_t dev)
>>>       int i;
>>>       drmDevicePtr device;
>>>   -    for (i = 0; i < MAX_CARDS_SUPPORTED && drm_amdgpu[i] >= 0; 
>>> i++) {
>>> +    for (i = 0; i < num_drm_devices && drm_amdgpu[i] >= 0; i++) {
>>>           if (drmGetDevice2(drm_amdgpu[i],
>>>               DRM_DEVICE_GET_PCI_REVISION,
>>>               &device) == 0) {
>>> @@ -456,10 +482,6 @@ int main(int argc, char **argv)
>>>       int display_list = 0;
>>>       int force_run = 0;
>>>   -    for (i = 0; i < MAX_CARDS_SUPPORTED; i++)
>>> -        drm_amdgpu[i] = -1;
>>> -
>>> -
>>>       /* Parse command line string */
>>>       opterr = 0;        /* Do not print error messages from getopt */
>>>       while ((c = getopt(argc, argv, options)) != -1) {
>>> diff --git a/tests/amdgpu/amdgpu_test.h b/tests/amdgpu/amdgpu_test.h
>>> index 62875736..8a604fe4 100644
>>> --- a/tests/amdgpu/amdgpu_test.h
>>> +++ b/tests/amdgpu/amdgpu_test.h
>>> @@ -27,13 +27,8 @@
>>>   #include "amdgpu.h"
>>>   #include "amdgpu_drm.h"
>>>   -/**
>>> - * Define max. number of card in system which we are able to handle
>>> - */
>>> -#define MAX_CARDS_SUPPORTED     4
>>> -
>>>   /* Forward reference for array to keep "drm" handles */
>>> -extern int drm_amdgpu[MAX_CARDS_SUPPORTED];
>>> +extern int *drm_amdgpu;
>>>     /* Global variables */
>>>   extern int open_render_node;
>>
>
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