[bug report] spi: imx: add a check for speed_hz before calculating the clock

[Dan Carpenter <dan.carpenter@xxxxxxxxxx>]

Hello Clark Wang,

The patch 4df2f5e1372e: "spi: imx: add a check for speed_hz before
calculating the clock" from Apr 8, 2021, leads to the following
Smatch static checker warning:

	drivers/spi/spi-imx.c:628 mx51_ecspi_prepare_transfer()
	error: uninitialized symbol 'clk'.

drivers/spi/spi-imx.c
    609 static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx,
    610                                        struct spi_device *spi)
    611 {
    612         u32 ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL);
    613         u32 clk;
                ^^^^^^^^
This use to be "clk = t->speed_hz"

    614 
    615         /* Clear BL field and set the right value */
    616         ctrl &= ~MX51_ECSPI_CTRL_BL_MASK;
    617         if (spi_imx->slave_mode && is_imx53_ecspi(spi_imx))
    618                 ctrl |= (spi_imx->slave_burst * 8 - 1)
    619                         << MX51_ECSPI_CTRL_BL_OFFSET;
    620         else
    621                 ctrl |= (spi_imx->bits_per_word - 1)
    622                         << MX51_ECSPI_CTRL_BL_OFFSET;
    623 
    624         /* set clock speed */
    625         ctrl &= ~(0xf << MX51_ECSPI_CTRL_POSTDIV_OFFSET |
    626                   0xf << MX51_ECSPI_CTRL_PREDIV_OFFSET);
    627         ctrl |= mx51_ecspi_clkdiv(spi_imx, spi_imx->spi_bus_clk, &clk);
                                                                         ^^^^
And then fixed here on the success path

--> 628         spi_imx->spi_bus_clk = clk;

Now if mx51_ecspi_clkdiv() fails it's uninitialized

    629 
    630         /*
    631          * ERR009165: work in XHC mode instead of SMC as PIO on the chips
    632          * before i.mx6ul.
    633          */
    634         if (spi_imx->usedma && spi_imx->devtype_data->tx_glitch_fixed)
    635                 ctrl |= MX51_ECSPI_CTRL_SMC;
    636         else
    637                 ctrl &= ~MX51_ECSPI_CTRL_SMC;
    638 
    639         writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
    640 
    641         return 0;
    642 }

regards,
dan carpenter