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SubjectRe: [PATCH 1/2] spi: octeontx2: Add support for octeontx2 spi controller
On Mon, Mar 27, 2023 at 11:07:52AM -0700, Piyush Malgujar wrote:

> +static int tbi_clk_en = 1;
> +module_param(tbi_clk_en, uint, 0644);
> +MODULE_PARM_DESC(tbi_clk_en,
> + "Use Fixed Time Base 100MHz Reference Clock (0=Disable, 1=Enable [default])");
> +
> +static int cfg_mode_delay = 30;
> +module_param(cfg_mode_delay, uint, 0644);
> +MODULE_PARM_DESC(cfg_mode_delay,
> + "Delay in micro-seconds for mode change in MPI CFG register (30 [default])");

These don't look like they should be configurable at runtime,
either DT or (especially in the second case) just have the driver
do the right thing.

> +static void octeontx2_spi_wait_ready(struct octeontx2_spi *p)
> +{
> + union mpix_sts mpi_sts;
> + unsigned int loops = 0;
> +
> + mpi_sts.u64 = 0;
> + do {
> + if (loops++)
> + __delay(500);
> + mpi_sts.u64 = readq(p->register_base + OCTEONTX2_SPI_STS(p));
> + } while (mpi_sts.s.busy);

Might want a cpu_relax() in there.

> + p->cs_enax |= (0xFull << 12);
> + mpi_cfg.u64 |= p->cs_enax;
> +
> + if (mpi_cfg.u64 != p->last_cfg) {
> + p->last_cfg = mpi_cfg.u64;
> + writeq(mpi_cfg.u64, p->register_base + OCTEONTX2_SPI_CFG(p));
> + mpi_cfg.u64 = readq(p->register_base + OCTEONTX2_SPI_CFG(p));
> + udelay(cfg_mode_delay); /* allow CS change to settle */
> + }

It looks like the hardware has independent control of chip select
so should just implement a set_cs() operation. That seems to be
the only thing stopping the driver using transfer_one() instead
of transfer_one_message() so it should do that too and save more
code.

> + p->clk = devm_clk_get(dev, NULL);
> + if (IS_ERR(p->clk)) {
> + p->clk = devm_clk_get(dev, "sclk");
> + p->sys_freq = 0;
> + } else {
> + ret = clk_prepare_enable(p->clk);
> + if (!ret)
> + p->sys_freq = clk_get_rate(p->clk);
> + }

We don't need to enable sclk or care about errors? That seems
buggy. The driver should just rely on the clock API here.

> + if (!p->sys_freq)
> + p->sys_freq = SYS_FREQ_DEFAULT;
> + if (tbi_clk_en)
> + p->sys_freq = TBI_FREQ;

We never seem to do anything to actually configure this in the
hardware.
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