Re: [PATCH v4 2/5] soc: qcom: llcc: Add regmap for Broadcast_AND region

[Konrad Dybcio]

On 4/2/24 21:34, Unnathi Chalicheemala wrote:
> On 3/30/2024 4:46 AM, Krzysztof Kozlowski wrote:
> > On 29/03/2024 22:53, Unnathi Chalicheemala wrote:
> > > Define new regmap structure for Broadcast_AND region and initialize
> > > this regmap when HW block version is greater than 4.1, otherwise
> > > initialize as a NULL pointer for backwards compatibility.
> >
> > > +	struct regmap *regmap;
> > >   	u32 act_ctrl_reg;
> > >   	u32 act_clear_reg;
> > >   	u32 status_reg;
> > > @@ -849,7 +850,8 @@ static int llcc_update_act_ctrl(u32 sid,
> > >   		return ret;
> > >   
> > >   	if (drv_data->version >= LLCC_VERSION_4_1_0_0) {
> > > -		ret = regmap_read_poll_timeout(drv_data->bcast_regmap, status_reg,
> > > +		regmap = drv_data->bcast_and_regmap ?: drv_data->bcast_regmap;
> > > +		ret = regmap_read_poll_timeout(regmap, status_reg,
> > >   				      slice_status, (slice_status & ACT_COMPLETE),
> > >   				      0, LLCC_STATUS_READ_DELAY);
> > >   		if (ret)
> > > @@ -1284,6 +1286,16 @@ static int qcom_llcc_probe(struct platform_device *pdev)
> > >   
> > >   	drv_data->version = version;
> > >   
> > > +	/* Applicable only when drv_data->version >= 4.1 */
> > > +	drv_data->bcast_and_regmap = qcom_llcc_init_mmio(pdev, i + 1, "llcc_broadcast_and_base");
> > > +	if (IS_ERR(drv_data->bcast_and_regmap)) {
> >
> > I am pretty sure this breaks all users. Can you please explain how do
> > you maintain ABI and that IS_ERR() is applied only for version >= 4.1?
> >
> > Best regards,
> > Krzysztof
> IS_ERR() check is done for all versions.
> If new register isn't defined in DT(for version < 4.1) it simply sets bcast_and_regmap to NULL.
> Otherwise, for version >= 4.1, it goes to err(in the case bcast_and_regmap isn't set properly).

b4 shazam <this series>

booting on 8250, I get:

[    2.794850] qcom-llcc 9200000.system-cache-controller: invalid resource (null)

which comes from lib/devres.c : __devm_ioremap_resource()

Now, this is gonna get you an angry Johan(+CC) response when he sees this land in
the next release. Perhaps, this warning could either be removed from libdevres,
or some sort of an _optional variant that doesn't print it could be introduced.

Konrad