Messages in this thread | | | Date | Tue, 9 Sep 2014 11:23:45 +0200 | Subject | Re: [PATCH v2 7/8] phy: miphy28lp: Add SSC support for PCIE | From | Gabriel Fernandez <> |
| |
Hi Kishon,
On 8 September 2014 17:15, Kishon Vijay Abraham I <kishon@ti.com> wrote: > > > On Wednesday 03 September 2014 09:07 PM, Gabriel FERNANDEZ wrote: >> SSC is the technique of modulating the operating frequency of a signal >> slightly to spread its radiated emissions over a range of frequencies. >> This reduction in the maximum emission for a given frequency helps meet >> radiated emission requirements. >> These settings are applicable for PCIE with Internal clock. >> >> Signed-off-by: Harsh Gupta <harsh.gupta@st.com> >> Signed-off-by: Gabriel Fernandez <gabriel.fernandez@linaro.orgm> >> --- >> drivers/phy/phy-miphy28lp.c | 32 ++++++++++++++++++++++++++++++++ >> 1 file changed, 32 insertions(+) >> >> diff --git a/drivers/phy/phy-miphy28lp.c b/drivers/phy/phy-miphy28lp.c >> index b36e737..976fdda 100644 >> --- a/drivers/phy/phy-miphy28lp.c >> +++ b/drivers/phy/phy-miphy28lp.c >> @@ -679,6 +679,36 @@ static int miphy28lp_init_sata(struct miphy28lp_phy *miphy_phy) >> return miphy_is_ready(miphy_phy); >> } >> >> +static void miphy_pcie_tune_ssc(struct miphy28lp_phy *miphy_phy) >> +{ >> + u8 val; >> + >> + /* Compensate Tx impedance to avoid out of range values */ >> + if (miphy_phy->ssc) { >> + /* >> + * Enable the SSC on PLL for all banks >> + * SSC Modulation @ 31 KHz and 4000 ppm modulation amp >> + */ >> + val = readb_relaxed(miphy_phy->base + 0x0c); >> + val |= 0x04; >> + writeb_relaxed(val, miphy_phy->base + 0x0c); >> + val = readb_relaxed(miphy_phy->base + 0x0a); >> + val |= 0x10; >> + writeb_relaxed(val, miphy_phy->base + 0x0a); > > macros for these registers and values is needed. Or else it's difficult to review. ok will be fix to v3
>> + >> + for (val = 0; val < 2; val++) { >> + writeb_relaxed(val, miphy_phy->base + 0x0f); >> + writeb_relaxed(0x69, miphy_phy->base + 0xe5); > > Do these registers have to be written for every iteration?
Yes because we select the bank value before (with val)
> > Thanks > Kishon
| |