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SubjectRe: [PATCH v2 2/2] spi: Add ADI driver for Spreadtrum platform
Hi Rob,

On 14 September 2017 at 03:45, Rob Herring <robh@kernel.org> wrote:
> On Fri, Sep 08, 2017 at 04:33:42PM +0800, Baolin Wang wrote:
>> This patch adds ADI driver based on SPI framework for
>> Spreadtrum SC9860 platform.
>>
>> Signed-off-by: Baolin Wang <baolin.wang@spreadtrum.com>
>> ---
>
> [...]
>
>> +++ b/drivers/spi/spi-sprd-adi.c
>> @@ -0,0 +1,419 @@
>> +/*
>> + * Copyright (C) 2017 Spreadtrum Communications Inc.
>> + *
>> + * SPDX-License-Identifier: (GPL-2.0+ OR MIT)
>
> Kernel code should generally not be MIT license.

OK. Will fix in next version.

>
> [...]
>
>> +static int sprd_adi_drain_fifo(struct sprd_adi *sadi)
>> +{
>> + u32 timeout = ADI_FIFO_DRAIN_TIMEOUT;
>> + u32 sts;
>> +
>> + do {
>> + sts = readl_relaxed(sadi->base + REG_ADI_ARM_FIFO_STS);
>> + if (sts & BIT_FIFO_EMPTY)
>> + break;
>> +
>> + cpu_relax();
>> + } while (--timeout);
>
> You can use readl_poll_timeout.

The readl_poll_timeout() function might be sleep, but we can not sleep
when reading/writing data through ADI controller, since the routine is
under hardware spinlock protection. Moreover it is usually very quick
to jump the loop and we no need to sleep here.

>
>> +
>> + if (timeout == 0) {
>> + dev_err(sadi->dev, "drain write fifo timeout\n");
>> + return -EBUSY;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int sprd_adi_fifo_is_full(struct sprd_adi *sadi)
>> +{
>> + return readl_relaxed(sadi->base + REG_ADI_ARM_FIFO_STS) & BIT_FIFO_FULL;
>> +}
>> +
>> +static int sprd_adi_read(struct sprd_adi *sadi, u32 reg_paddr, u32 *read_val)
>> +{
>> + int read_timeout = ADI_READ_TIMEOUT;
>> + u32 val, rd_addr;
>> +
>> + /*
>> + * Set the physical register address need to read into RD_CMD register,
>> + * then ADI controller will start to transfer automatically.
>> + */
>> + writel_relaxed(reg_paddr, sadi->base + REG_ADI_RD_CMD);
>> +
>> + /*
>> + * Wait read operation complete, the BIT_RD_CMD_BUSY will be set
>> + * simultaneously when writing read command to register, and the
>> + * BIT_RD_CMD_BUSY will be cleared after the read operation is
>> + * completed.
>> + */
>> + do {
>> + val = readl_relaxed(sadi->base + REG_ADI_RD_DATA);
>> + if (!(val & BIT_RD_CMD_BUSY))
>> + break;
>> +
>> + cpu_relax();
>> + } while (--read_timeout);
>
> readl_poll_timeout

The same reason as above. Thanks for your comments.

--
Baolin.wang
Best Regards

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