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SubjectRe: [PATCH 1/4] dma: Add PTDMA Engine driver support
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On 9/25/2019 12:42 AM, Vinod Koul wrote:
> [CAUTION: External Email]
>
> On 24-09-19, 07:31, Mehta, Sanju wrote:
>> From: Sanjay R Mehta <sanju.mehta@amd.com>
>>
>> This is the driver for the AMD passthrough DMA Engine
> Please fix threading for your series, they are all over my inbox :(
This will be taken care in next version of patch set.
>
>> +#include "ptdma.h"
>> +
>> +/* Union to define the function field (cmd_reg1/dword0) */
>> +union pt_function {
>> + struct {
>> + u16 byteswap:2;
>> + u16 bitwise:3;
>> + u16 reflect:2;
>> + u16 rsvd:8;
>> + } pt;
>> + u16 raw;
>> +};
> So IIUC you are using this to write to hw registers, what is wrong with
> defining bit fields for registers using BIT and GENMASK and then write
> the settings to the hardware. That IMHO looks much neater!
Agreed. This will be taken care in next version of patch set.
>
>> +static inline u32 low_address(unsigned long addr)
>> +{
>> + return (u64)addr & 0x0ffffffff;
>> +}
>> +
>> +static inline u32 high_address(unsigned long addr)
>> +{
>> + return ((u64)addr >> 32) & 0x00000ffff;
>> +}
> Use lower_32_bits() and upper_32_bits() please. Also check the APIs in
> kernel and don't invent your own!
Agreed. This will be taken care in next version of patch set.
>
>> +int pt_core_perform_passthru(struct pt_op *op)
>> +{
>> + struct ptdma_desc desc;
>> + union pt_function function;
>> + struct pt_dma_info *saddr = &op->src.u.dma;
>> +
>> + memset(&desc, 0, Q_DESC_SIZE);
>> +
>> + PT_CMD_ENGINE(&desc) = PT_ENGINE_PASSTHRU;
>> +
>> + PT_CMD_SOC(&desc) = 0;
>> + PT_CMD_IOC(&desc) = 1;
>> + PT_CMD_INIT(&desc) = 0;
>> + PT_CMD_EOM(&desc) = op->eom;
>> + PT_CMD_PROT(&desc) = 0;
>> +
>> + function.raw = 0;
>> + PT_BYTESWAP(&function) = op->passthru.byte_swap;
>> + PT_BITWISE(&function) = op->passthru.bit_mod;
>> + PT_CMD_FUNCTION(&desc) = function.raw;
>> +
>> + PT_CMD_LEN(&desc) = saddr->length;
>> +
>> + PT_CMD_SRC_LO(&desc) = pt_addr_lo(&op->src.u.dma);
>> + PT_CMD_SRC_HI(&desc) = pt_addr_hi(&op->src.u.dma);
>> + PT_CMD_SRC_MEM(&desc) = PT_MEMTYPE_SYSTEM;
>> +
>> + PT_CMD_DST_LO(&desc) = pt_addr_lo(&op->dst.u.dma);
>> + PT_CMD_DST_HI(&desc) = pt_addr_hi(&op->dst.u.dma);
>> + PT_CMD_DST_MEM(&desc) = PT_MEMTYPE_SYSTEM;
> This really looks bad, as I siad please use bits and genmasks. Also see
> how other driver handles registers transparently!
Agreed. This will be taken care in next version of patch set.
>
>> +static irqreturn_t pt_core_irq_handler(int irq, void *data)
>> +{
>> + struct pt_device *pt = (struct pt_device *)data;
>> +
>> + pt_core_disable_queue_interrupts(pt);
>> + tasklet_schedule(&pt->irq_tasklet);
> Why are you not submitting txn in ISR, you are keeping dmaengine idle
> for tasklet!
Agreed. This will be taken care in next version of patch set.
>
>> + cmd_q->qidx = 0;
>> + /* Preset some register values and masks that are queue
>> + * number dependent
>> + */
> kernel style is
> /*
> * this is a multi line comment
> * notice first and last line
> */
>
>> + cmd_q->reg_control = pt->io_regs + CMD_Q_STATUS_INCR;
>> + cmd_q->reg_tail_lo = cmd_q->reg_control + CMD_Q_TAIL_LO_BASE;
>> + cmd_q->reg_head_lo = cmd_q->reg_control + CMD_Q_HEAD_LO_BASE;
>> + cmd_q->reg_int_enable = cmd_q->reg_control +
>> + CMD_Q_INT_ENABLE_BASE;
>> + cmd_q->reg_interrupt_status = cmd_q->reg_control +
>> + CMD_Q_INTERRUPT_STATUS_BASE;
>> + cmd_q->reg_status = cmd_q->reg_control + CMD_Q_STATUS_BASE;
>> + cmd_q->reg_int_status = cmd_q->reg_control +
>> + CMD_Q_INT_STATUS_BASE;
>> + cmd_q->reg_dma_status = cmd_q->reg_control +
>> + CMD_Q_DMA_STATUS_BASE;
>> + cmd_q->reg_dma_read_status = cmd_q->reg_control +
>> + CMD_Q_DMA_READ_STATUS_BASE;
>> + cmd_q->reg_dma_write_status = cmd_q->reg_control +
>> + CMD_Q_DMA_WRITE_STATUS_BASE;
>> +
>> + init_waitqueue_head(&cmd_q->int_queue);
>> +
>> + dev_dbg(dev, "queue available\n");
> Noise
This will be taken care in next version of patch set.
>
>> +
>> + /* Turn off the queues and disable interrupts until ready */
>> + pt_core_disable_queue_interrupts(pt);
>> +
>> + cmd_q->qcontrol = 0; /* Start with nothing */
>> + iowrite32(cmd_q->qcontrol, cmd_q->reg_control);
>> +
>> + ioread32(cmd_q->reg_int_status);
>> + ioread32(cmd_q->reg_status);
>> +
>> + /* Clear the interrupt status */
>> + iowrite32(SUPPORTED_INTERRUPTS, cmd_q->reg_interrupt_status);
>> +
>> + dev_dbg(dev, "Requesting an IRQ...\n");
>> + /* Request an irq */
>> + ret = request_irq(pt->pt_irq, pt_core_irq_handler, 0, "pt", pt);
>> + if (ret) {
>> + dev_err(dev, "unable to allocate an IRQ\n");
>> + goto e_pool;
>> + }
>> + /* Initialize the ISR tasklet */
>> + tasklet_init(&pt->irq_tasklet, pt_core_irq_bh,
>> + (unsigned long)pt);
>> +
>> + dev_dbg(dev, "Configuring virtual queues...\n");
>> + /* Configure size of each virtual queue accessible to host */
>> +
>> + cmd_q->qcontrol &= ~(CMD_Q_SIZE << CMD_Q_SHIFT);
>> + cmd_q->qcontrol |= QUEUE_SIZE_VAL << CMD_Q_SHIFT;
>> +
>> + cmd_q->qdma_tail = cmd_q->qbase_dma;
>> + dma_addr_lo = low_address(cmd_q->qdma_tail);
>> + iowrite32((u32)dma_addr_lo, cmd_q->reg_tail_lo);
>> + iowrite32((u32)dma_addr_lo, cmd_q->reg_head_lo);
>> +
>> + dma_addr_hi = high_address(cmd_q->qdma_tail);
>> + cmd_q->qcontrol |= (dma_addr_hi << 16);
>> + iowrite32(cmd_q->qcontrol, cmd_q->reg_control);
>> +
>> + dev_dbg(dev, "Starting threads...\n");
>> + /* Create a kthread for command queue */
>> +
>> + kthread = kthread_create(pt_cmd_queue_thread, cmd_q, "pt-q");
> Why do you need a thread, you already have a tasklet?
Agreed. This will be taken care in next version of patch set.
>
>
> Okay am stopping here. There are **tons** of style issues with the
> series. For this patch alone checkpatch tells me:
>
> total: 184 errors, 12 warnings, 31 checks, 1593 lines checked
It appears that MS exchange reformatted the patch and the errors are because of Special characters. Now that I am aware of the issue, this will be addressed in next version of patch set.
>
> 1. Please **FIX** the errors
> 2. I suspect tab spaces are wrong (we use 8)
> 3. Read Documentation/process/coding-style.rst, if done, re read it
> again
> 4. Use dmaengine APIs and virtual dma layer
> 5. Dont invent your own stuff, kernel already has stuff to deal with
> most common thngs, no your case is not unique.
> 6. Check other drivers on how to do things
> 7. Make sure you send a series as athread, if in doubt send to yourself!
Sure. All of your suggestion will be addressed in next version of patch set.
>
> Thanks
> --
> ~Vinod
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