[PATCH v5 4/7] accel/ivpu: Add IPC driver and JSM messages

[Jacek Lawrynowicz]

Hi,

On 12.01.2023 19:18, Jeffrey Hugo wrote:
> On 1/9/2023 5:23 AM, Jacek Lawrynowicz wrote:
>> The IPC driver is used to send and receive messages to/from firmware
>> running on the VPU.
>>
>> The only supported IPC message format is Job Submission Model (JSM)
>> defined in vpu_jsm_api.h header.
>>
>> Co-developed-by: Andrzej Kacprowski <andrzej.kacprowski at linux.intel.com>
>> Signed-off-by: Andrzej Kacprowski <andrzej.kacprowski at linux.intel.com>
>> Co-developed-by: Krystian Pradzynski <krystian.pradzynski at linux.intel.com>
>> Signed-off-by: Krystian Pradzynski <krystian.pradzynski at linux.intel.com>
>> Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz at linux.intel.com>
> 
> Reviewed-by: Jeffrey Hugo <quic_jhugo at quicinc.com>
> 
>> +int ivpu_ipc_irq_handler(struct ivpu_device *vdev)
>> +{
>> +    struct ivpu_ipc_info *ipc = vdev->ipc;
>> +    struct ivpu_ipc_consumer *cons;
>> +    struct ivpu_ipc_hdr *ipc_hdr;
>> +    struct vpu_jsm_msg *jsm_msg;
>> +    unsigned long flags;
>> +    bool dispatched;
>> +    u32 vpu_addr;
>> +
>> +    /* Driver needs to purge all messages from IPC FIFO to clear IPC interrupt.
>> +     * Without purge IPC FIFO to 0 next IPC interrupts won't be generated.
>> +     */
>> +    while (ivpu_hw_reg_ipc_rx_count_get(vdev)) {
> 
> Ick.  Please no in the long term?
> 
> This is an infinite loop.  In hard IRQ context.  Controlled by the device, which you probably shouldn't trust.
> 
> However the real fix for this is to move to threaded_irqs.  Which is going to be a huge refactor for you.  Rate limiting doesn't appear viable.
> 
> If I understand things correctly, the chances that the device will generate a large count, or update the count as fast or faster than the driver are low, but it should still be fixed.
> 
> How about a high priority todo to convert to threaded irqs?  At the same time you can update the return value for this function which seems to not be checked anywhere, and also the comment here which is not proper multi-line style.

OK, I've added this at the top of the TODO and fixed the comment.
Regarding the ivpu_ipc_irq_handler() return code it is checked in the next patch in ivpu_wait_for_ready().

Regards,
Jacek