Hi Andi:
Thank you for your comments.
Andi Shyti <andi.shyti@xxxxxxxxxx> 於 2024年10月24日 週四 下午6:20寫道：
>
> Hi Tyrone,
>
> ...
>
> > - /* 100KHz and below: */
> > - if (bus_freq_hz <= I2C_MAX_STANDARD_MODE_FREQ) {
> > - sclfrq = src_clk_khz / (bus_freq_khz * 4);
> > -
> > - if (sclfrq < SCLFRQ_MIN || sclfrq > SCLFRQ_MAX)
> > - return -EDOM;
> > -
> > - if (src_clk_khz >= 40000)
> > - hldt = 17;
> > - else if (src_clk_khz >= 12500)
> > - hldt = 15;
> > - else
> > - hldt = 7;
> > - }
> > -
> > - /* 400KHz: */
> > - else if (bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ) {
> > - sclfrq = 0;
> > + switch (bus_freq_hz) {
> > + case I2C_MAX_STANDARD_MODE_FREQ:
> > + smb_timing = smb_timing_100khz;
> > + table_size = ARRAY_SIZE(smb_timing_100khz);
> > + break;
> > + case I2C_MAX_FAST_MODE_FREQ:
> > + smb_timing = smb_timing_400khz;
> > + table_size = ARRAY_SIZE(smb_timing_400khz);
> > fast_mode = I2CCTL3_400K_MODE;
> > -
> > - if (src_clk_khz < 7500)
> > - /* 400KHZ cannot be supported for core clock < 7.5MHz */
> > - return -EDOM;
> > -
> > - else if (src_clk_khz >= 50000) {
> > - k1 = 80;
> > - k2 = 48;
> > - hldt = 12;
> > - dbnct = 7;
> > - }
> > -
> > - /* Master or Slave with frequency > 25MHz */
> > - else if (src_clk_khz > 25000) {
> > - hldt = clk_coef(src_clk_khz, 300) + 7;
> > - k1 = clk_coef(src_clk_khz, 1600);
> > - k2 = clk_coef(src_clk_khz, 900);
> > - }
> > - }
> > -
> > - /* 1MHz: */
> > - else if (bus_freq_hz <= I2C_MAX_FAST_MODE_PLUS_FREQ) {
> > - sclfrq = 0;
> > + break;
> > + case I2C_MAX_FAST_MODE_PLUS_FREQ:
> > + smb_timing = smb_timing_1000khz;
> > + table_size = ARRAY_SIZE(smb_timing_1000khz);
> > fast_mode = I2CCTL3_400K_MODE;
> > -
> > - /* 1MHZ cannot be supported for core clock < 24 MHz */
> > - if (src_clk_khz < 24000)
> > - return -EDOM;
> > -
> > - k1 = clk_coef(src_clk_khz, 620);
> > - k2 = clk_coef(src_clk_khz, 380);
> > -
> > - /* Core clk > 40 MHz */
> > - if (src_clk_khz > 40000) {
> > - /*
> > - * Set HLDT:
> > - * SDA hold time: (HLDT-7) * T(CLK) >= 120
> > - * HLDT = 120/T(CLK) + 7 = 120 * FREQ(CLK) + 7
> > - */
> > - hldt = clk_coef(src_clk_khz, 120) + 7;
> > - } else {
> > - hldt = 7;
> > - dbnct = 2;
> > - }
> > + break;
> > + default:
> > + return -EINVAL;
>
> There is here a slight change of behaiour which is not mentioned
> in the commit log. Before the user could set a bus_freq_hz which
> had to be <= I2C_MAX_..._MODE_FREQ, while now it has to be
> precisely that.
>
> Do we want to check what the user has set in the DTS?
The driver checks the bus frequency the user sets in the DTS.
Please refer to the links:
1. https://github.com/torvalds/linux/blob/master/drivers/i2c/busses/i2c-npcm7xx.c#L1995
2. https://github.com/torvalds/linux/blob/master/drivers/i2c/busses/i2c-npcm7xx.c#L2002
>
> (Or am I missing something?)
>
> Thanks,
> Andi
Thank you.
Regards,
Tyrone
