Re: [PATCH v4 3/6] PCI: mediatek-gen3: Move reset/assert callbacks in .power_up()

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On Mo, 2024-11-18 at 10:03 +0100, Lorenzo Bianconi wrote:
> On Nov 18, Philipp Zabel wrote:
> > On Mo, 2024-11-18 at 09:04 +0100, Lorenzo Bianconi wrote:
> > > In order to make the code more readable, the reset_control_bulk_assert()
> > > for PHY reset lines is moved to make it pair with
> > > reset_control_bulk_deassert() in mtk_pcie_power_up() and
> > > mtk_pcie_en7581_power_up(). The same change is done for
> > > reset_control_assert() used to assert MAC reset line.
> > > 
> > > Introduce PCIE_MTK_RESET_TIME_US macro for the time needed to
> > > complete PCIe reset on MediaTek controller.
> > > 
> > > Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> > > Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> > > ---
> > >  drivers/pci/controller/pcie-mediatek-gen3.c | 27 +++++++++++++++++++--------
> > >  1 file changed, 19 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
> > > index 3cfcb45d31508142d28d338ff213f70de9b4e608..2b80edd4462ad4e9f2a5d192db7f99307113eb8a 100644
> > > --- a/drivers/pci/controller/pcie-mediatek-gen3.c
> > > +++ b/drivers/pci/controller/pcie-mediatek-gen3.c
> > > @@ -125,6 +125,8 @@
> > >  
> > >  #define MAX_NUM_PHY_RESETS		3
> > >  
> > > +#define PCIE_MTK_RESET_TIME_US		10
> > > +
> > >  /* Time in ms needed to complete PCIe reset on EN7581 SoC */
> > >  #define PCIE_EN7581_RESET_TIME_MS	100
> > >  
> > > @@ -912,6 +914,14 @@ static int mtk_pcie_en7581_power_up(struct mtk_gen3_pcie *pcie)
> > >  	int err;
> > >  	u32 val;
> > >  
> > > +	/*
> > > +	 * The controller may have been left out of reset by the bootloader
> > > +	 * so make sure that we get a clean start by asserting resets here.
> > > +	 */
> > > +	reset_control_bulk_assert(pcie->soc->phy_resets.num_resets,
> > > +				  pcie->phy_resets);
> > > +	reset_control_assert(pcie->mac_reset);
> > > +
> > >  	/*
> > >  	 * Wait for the time needed to complete the bulk assert in
> > >  	 * mtk_pcie_setup for EN7581 SoC.
> > 
> > This comment is not correct anymore.
> 
> I agree naming is hard, but I guess we can assume with 'bulk' we refer to both
> phy and mac reset (similar to what we have in mtk_pcie_power_up()),
> what do you think?

My point is that the referenced (bulk) assert isn't in mtk_pcie_setup()
anymore - it was just moved right above this comment.

I wonder why that delay is required at all, though. Does the reset
controller driver return from reset_control_ops::assert before the
reset line to the PCI controller is asserted?

regards
Philipp





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