linux-kernel - Re: [PATCH V4 05/16] PCI: dwc: Move config space capability search API

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Date:   Tue, 23 Apr 2019 15:32:44 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Vidya Sagar <vidyas@...dia.com>
Cc:     lorenzo.pieralisi@....com, robh+dt@...nel.org,
        mark.rutland@....com, thierry.reding@...il.com,
        jonathanh@...dia.com, kishon@...com, catalin.marinas@....com,
        will.deacon@....com, jingoohan1@...il.com,
        gustavo.pimentel@...opsys.com, mperttunen@...dia.com,
        linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kthota@...dia.com,
        mmaddireddy@...dia.com, sagar.tv@...il.com
Subject: Re: [PATCH V4 05/16] PCI: dwc: Move config space capability search
 API

On Tue, Apr 23, 2019 at 01:57:19PM +0530, Vidya Sagar wrote:
> Move PCIe config space capability search API to common DesignWare file
> as this can be used by both host and ep mode codes.
> 
> Signed-off-by: Vidya Sagar <vidyas@...dia.com>
> Acked-by: Gustavo Pimentel <gustavo.pimentel@...opsys.com>
> ---
> Changes from [v3]:
> * Rebased to linux-next top of the tree
> 
> Changes from [v2]:
> * None
> 
> Changes from [v1]:
> * Removed dw_pcie_find_next_ext_capability() API from here and made a
>   separate patch for that
> 
>  drivers/pci/controller/dwc/pcie-designware.c | 33 ++++++++++++++++++++
>  drivers/pci/controller/dwc/pcie-designware.h |  2 ++

You claim this is a "move", but I only see adds.  Where did it move
*from*?

While you're at it, can you add a comment in the code about why we
can't use the regular pci_find_capability() interface?  It's really a
shame to have to reimplement that.

>  2 files changed, 35 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> index 8e0081ccf83b..6a98135244d6 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.c
> +++ b/drivers/pci/controller/dwc/pcie-designware.c
> @@ -20,6 +20,39 @@
>  #define PCIE_PHY_DEBUG_R1_LINK_UP	(0x1 << 4)
>  #define PCIE_PHY_DEBUG_R1_LINK_IN_TRAINING	(0x1 << 29)
>  
> +static u8 __dw_pcie_find_next_cap(struct dw_pcie *pci, u8 cap_ptr,
> +				  u8 cap)
> +{
> +	u8 cap_id, next_cap_ptr;
> +	u16 reg;
> +
> +	reg = dw_pcie_readw_dbi(pci, cap_ptr);
> +	next_cap_ptr = (reg & 0xff00) >> 8;
> +	cap_id = (reg & 0x00ff);
> +
> +	if (!next_cap_ptr || cap_id > PCI_CAP_ID_MAX)
> +		return 0;
> +
> +	if (cap_id == cap)
> +		return cap_ptr;
> +
> +	return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap);
> +}
> +
> +u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap)
> +{
> +	u8 next_cap_ptr;
> +	u16 reg;
> +
> +	reg = dw_pcie_readw_dbi(pci, PCI_CAPABILITY_LIST);
> +	next_cap_ptr = (reg & 0x00ff);
> +
> +	if (!next_cap_ptr)
> +		return 0;
> +
> +	return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap);
> +}
> +
>  int dw_pcie_read(void __iomem *addr, int size, u32 *val)
>  {
>  	if (!IS_ALIGNED((uintptr_t)addr, size)) {
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 9ee98ced1ef6..35160b4ce929 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -248,6 +248,8 @@ struct dw_pcie {
>  #define to_dw_pcie_from_ep(endpoint)   \
>  		container_of((endpoint), struct dw_pcie, ep)
>  
> +u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap);
> +
>  int dw_pcie_read(void __iomem *addr, int size, u32 *val);
>  int dw_pcie_write(void __iomem *addr, int size, u32 val);
>  
> -- 
> 2.17.1
>