Re: [PATCH v2 2/2] i2c: qcom-geni: add I2C frequency table for 32 MHz firmware-based SEs

[Praveen Talari]

Hi Kanthiravan,

On 26-08-2026 22:29, Kathiravan Thirumoorthy wrote:
> On 8/25/2026 10:50 PM, Praveen Talari wrote:
> > Hi Kathiravan,
> >
> > On 12-08-2026 14:00, Kathiravan Thirumoorthy wrote:
> > > On IPQ5424, the I2C controller can operate on both RTL-hardened SEs
> > > and firmware-based SEs. As documented in commit 506bb2ab0075
> > > ("i2c: qcom-geni: Support systems with 32MHz serial engine clock"),
> > > in IPQ5424 SEs use a 32 MHz source clock.
> > >
> > > The existing frequency table does not provide the required SCL timing
> > > parameters for firmware-based SEs. Add a dedicated frequency table
> > > using the SCL counter values recommended by the hardware design team
> > > and select it for firmware-based SEs to achieve the target bus
> > > frequencies.
> > >
> > > Move geni_i2c_clk_map_idx() from geni_i2c_resources_init() to
> > > geni_i2c_init() to ensure SE_HW_PARAM_2 is accessed only after the
> > > required clocks have been enabled.
> > >
> > > Signed-off-by: Kathiravan Thirumoorthy 
> > > <kathiravan.thirumoorthy@xxxxxxxxxxxxxxxx>
> > > ---
> > >   drivers/i2c/busses/i2c-qcom-geni.c | 25 ++++++++++++++++++-------
> > >   include/linux/soc/qcom/geni-se.h   |  1 +
> > >   2 files changed, 19 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/i2c/busses/i2c-qcom-geni.c 
> > > b/drivers/i2c/busses/i2c-qcom-geni.c
> > > index 00013b41a6f5..15835f10b062 100644
> > > --- a/drivers/i2c/busses/i2c-qcom-geni.c
> > > +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> > > @@ -187,19 +187,28 @@ static const struct geni_i2c_clk_fld 
> > > geni_i2c_clk_map_19p2mhz[] = {
> > >   };
> > >     /* source_clock = 32 MHz */
> > > -static const struct geni_i2c_clk_fld geni_i2c_clk_map_32mhz[] = {
> > > +static const struct geni_i2c_clk_fld 
> > > geni_i2c_clk_map_32mhz_minicore[] = {
> > >       { I2C_MAX_STANDARD_MODE_FREQ, 12, 9, 10, 26 },
> > >       { I2C_MAX_FAST_MODE_FREQ, 4, 3, 9, 19 },
> > >       { I2C_MAX_FAST_MODE_PLUS_FREQ, 2, 3, 5, 15 },
> > >       {}
> > >   };
> > >   +static const struct geni_i2c_clk_fld 
> > > geni_i2c_clk_map_32mhz_fwcore[] = {
> > > +    { I2C_MAX_STANDARD_MODE_FREQ, 12, 9, 10, 25 },
> > > +    { I2C_MAX_FAST_MODE_FREQ, 4, 3, 9, 18 },
> > > +    { I2C_MAX_FAST_MODE_PLUS_FREQ, 1, 6, 15, 29 },
> > > +    {}
> > > +};
> > > +
> > >   static int geni_i2c_clk_map_idx(struct geni_i2c_dev *gi2c)
> > >   {
> > >       const struct geni_i2c_clk_fld *itr;
> > > +    bool is_minicore = FIELD_GET(GEN_USE_MINICORES,
> > > +                     readl_relaxed(gi2c->se.base + SE_HW_PARAM_2));
> > >         if (clk_get_rate(gi2c->se.clk) == 32 * HZ_PER_MHZ)
> > > -        itr = geni_i2c_clk_map_32mhz;
> > > +        itr = is_minicore ? geni_i2c_clk_map_32mhz_minicore : 
> > > geni_i2c_clk_map_32mhz_fwcore;
> > The source selection remains unchanged when using 32 MHz:
> > writel_relaxed(0, gi2c->se.base + SE_GENI_CLK_SEL);
>
> I have to check on this. But in downstream, we didn't change this 
> configuration.

You might not have encountered any issues because SPI and UART already 
request

the necessary performance vote when operating at higher source clock 
frequencies.

Without the corresponding vote from SPI and UART, we would expect 
failures or

timing issues when switching to those higher frequencies for I2C.

> > However, what about the voltage requirements associated with the 
> > higher frequency?
>
> There are no such requirements in the IPQ SoC.

If there are no additional voltage requirements for I2C,

how are higher source clock frequencies handled for the SPI and UART 
GENI drivers?

They also operate at source frequencies above 19.2 MHz.

> > Are they automatically managed by the underlying provider, or is 
> > additional handling needed in the driver?
> >
> > Reference of konrad change for CCI I2C driver for 37.5MHz with 
> > voltage requirement.
> >
> > https://lore.kernel.org/linux-arm-msm/20250904-topic-cci_updates-v1-4-d38559692703@xxxxxxxxxxxxxxxx/ 
> >
> >
> >
> > Thanks,
> >
> > Praveen Talari