Hi Biju, On Tue, Jan 7, 2025 at 12:25 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote: > > Hi Prabhakar, > > > -----Original Message----- > > From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx> > > Sent: 07 January 2025 11:46 > > Subject: Re: [PATCH v3 4/6] clk: renesas: rzv2h: Switch MSTOP configuration to per-bit basis > > > > Hi Biju, > > > > On Tue, Jan 7, 2025 at 11:24 AM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote: > > > > > > Hi Prabhakar, > > > > > > Thanks for the patch. > > > > > > > -----Original Message----- > > > > From: Prabhakar <prabhakar.csengg@xxxxxxxxx> > > > > Sent: 02 January 2025 18:19 > > > > Subject: [PATCH v3 4/6] clk: renesas: rzv2h: Switch MSTOP > > > > configuration to per-bit basis > > > > > > > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx> > > > > > > > > Switch MSTOP handling from group-based to per-bit configuration to > > > > address issues with shared dependencies between module clocks. In > > > > the current group-based configuration, multiple module clocks may > > > > rely on a single MSTOP bit. When both clocks are turned ON and one > > > > is subsequently turned OFF, the shared MSTOP bit will still be set, which is incorrect since the > > other dependent module clock remains ON. > > > > > > I guess this statement is incorrect. Still in group-based, mstop bit is controlled by usage > > count(ref_cnt). > > > > > It is valid, consider an example say IP-A reuiqres MSTOP bits 8 | 9 | > > 10 and consider IP-B requires MSTOP bits 10 | 11 | 12 (of the same MSTOP register say MSTOP1). Now > > this will be seperate groups having separate count(ref_cnt). Say you turn ON IP-A module clock and > > correspondingly clear the MSTOP bits and similarly now lets turn ON module clocks for IP-B and clear > > the MSTOP bits. Now let's say you want to turn OFF IP-A so you turn OFF module clock and set the MSTOP > > bits 8 | 9 | 10. In this case you will now see issues with IP-B as MSTOP BIT(10) has been set when we > > turned OFF IP-A block. This case is handled by switching refcount on per mstop bit by this patch. > > I agree, Do we have such use case? > Yes, for USB2.0 on RZ/V2H. > Consider another use case, index 0, bit 8| index 0, bit9| index0, bit10 and index 0, bit8 | index1, bit 0 | index1 10 is addressed in current patch series? > Can you please elaborate, the above isn't clear to me. Cheers, Prabhakar
