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Re: [PATCH v2 1/5] PCI: rockchip: fix sign issues for current limits

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  Re: [PATCH v2 1/5] PCI: rockchip: fix sign issues for current limits Bjorn Helgaas <helgaas@kernel.org> - 2017-03-23 23:30 +0100
    Re: [PATCH v2 1/5] PCI: rockchip: fix sign issues for current limits Brian Norris <briannorris@chromium.org> - 2017-03-23 23:40 +0100
      Re: [PATCH v2 1/5] PCI: rockchip: fix sign issues for current limits Shawn Lin <shawn.lin@rock-chips.com> - 2017-03-24 02:30 +0100

#1607988 — Re: [PATCH v2 1/5] PCI: rockchip: fix sign issues for current limits

On Thu, Mar 09, 2017 at 06:46:13PM -0800, Brian Norris wrote:
> The regulator framework can return negative error codes via
> regulator_get_current_limit() for regulators that don't provide current
> information. The subsequent check for postive values isn't very useful,
> if the variable is unsigned.
> 
> Let's just match the signedness of the return value.
> 
> Prevents error messages like this, seen on Samsung Chromebook Plus:
> 
> [    1.069372] rockchip-pcie f8000000.pcie: invalid power supply
> 
> Fixes: 4816c4c7b82b ("PCI: rockchip: Provide captured slot power limit and scale")
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> Acked-by: Shawn Lin <shawn.lin@rock-chips.com>

I applied the first two patches (this already has Shawn's ack and the
second is trivially obvious) to pci/host-rockchip.  I'm not sure what the
current state of the others is.

I also applied the appended trivial indentation patch.

> ---
> v2: add Shawn's ack
> ---
>  drivers/pci/host/pcie-rockchip.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c
> index 26ddd3535272..d785f64ec03b 100644
> --- a/drivers/pci/host/pcie-rockchip.c
> +++ b/drivers/pci/host/pcie-rockchip.c
> @@ -425,7 +425,8 @@ static struct pci_ops rockchip_pcie_ops = {
>  
>  static void rockchip_pcie_set_power_limit(struct rockchip_pcie *rockchip)
>  {
> -	u32 status, curr, scale, power;
> +	int curr;
> +	u32 status, scale, power;
>  
>  	if (IS_ERR(rockchip->vpcie3v3))
>  		return;
> -- 
> 2.12.0.246.ga2ecc84866-goog
> 

commit 73edd2b180a18024605c599074596a9e22d745d6
Author: Bjorn Helgaas <bhelgaas@google.com>
Date:   Thu Mar 23 17:21:26 2017 -0500

    PCI: rockchip: Unindent rockchip_pcie_set_power_limit()
    
    If regulator_get_current_limit() returns 0 or error, return early so the
    body of the function doesn't have to be indented as the body of an "if"
    statement.  No functional change intended.
    
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c
index d785f64ec03b..7f76ff6af0ba 100644
--- a/drivers/pci/host/pcie-rockchip.c
+++ b/drivers/pci/host/pcie-rockchip.c
@@ -438,24 +438,25 @@ static void rockchip_pcie_set_power_limit(struct rockchip_pcie *rockchip)
 	 * to the actual power supply.
 	 */
 	curr = regulator_get_current_limit(rockchip->vpcie3v3);
-	if (curr > 0) {
-		scale = 3; /* 0.001x */
-		curr = curr / 1000; /* convert to mA */
-		power = (curr * 3300) / 1000; /* milliwatt */
-		while (power > PCIE_RC_CONFIG_DCR_CSPL_LIMIT) {
-			if (!scale) {
-				dev_warn(rockchip->dev, "invalid power supply\n");
-				return;
-			}
-			scale--;
-			power = power / 10;
-		}
+	if (curr <= 0)
+		return;
 
-		status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_DCR);
-		status |= (power << PCIE_RC_CONFIG_DCR_CSPL_SHIFT) |
-			  (scale << PCIE_RC_CONFIG_DCR_CPLS_SHIFT);
-		rockchip_pcie_write(rockchip, status, PCIE_RC_CONFIG_DCR);
+	scale = 3; /* 0.001x */
+	curr = curr / 1000; /* convert to mA */
+	power = (curr * 3300) / 1000; /* milliwatt */
+	while (power > PCIE_RC_CONFIG_DCR_CSPL_LIMIT) {
+		if (!scale) {
+			dev_warn(rockchip->dev, "invalid power supply\n");
+			return;
+		}
+		scale--;
+		power = power / 10;
 	}
+
+	status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_DCR);
+	status |= (power << PCIE_RC_CONFIG_DCR_CSPL_SHIFT) |
+		  (scale << PCIE_RC_CONFIG_DCR_CPLS_SHIFT);
+	rockchip_pcie_write(rockchip, status, PCIE_RC_CONFIG_DCR);
 }
 
 /**

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#1607995

On Thu, Mar 23, 2017 at 05:27:17PM -0500, Bjorn Helgaas wrote:
> On Thu, Mar 09, 2017 at 06:46:13PM -0800, Brian Norris wrote:
> > The regulator framework can return negative error codes via
> > regulator_get_current_limit() for regulators that don't provide current
> > information. The subsequent check for postive values isn't very useful,
> > if the variable is unsigned.
> > 
> > Let's just match the signedness of the return value.
> > 
> > Prevents error messages like this, seen on Samsung Chromebook Plus:
> > 
> > [    1.069372] rockchip-pcie f8000000.pcie: invalid power supply
> > 
> > Fixes: 4816c4c7b82b ("PCI: rockchip: Provide captured slot power limit and scale")
> > Signed-off-by: Brian Norris <briannorris@chromium.org>
> > Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
> 
> I applied the first two patches (this already has Shawn's ack and the
> second is trivially obvious) to pci/host-rockchip.

Thanks!

> I'm not sure what the
> current state of the others is.

Patch 4 seems like it should be fine (it was discussed previously, but
never done).

Apart from existing leaks in the PCI framework (which Jeffy and Shawn
are trying to patch [1]), I don't think there are any known issues with
3 and 5. It's certainly better than having 100% broken unbind at least,
IMO.

I suppose it's worth getting an ack/nack from Shawn though.

Brian

[1] https://patchwork.kernel.org/patch/9638353/
    https://patchwork.kernel.org/patch/9640545/
    https://patchwork.kernel.org/patch/9640549/

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#1608062

Hi Bjorn,

On 2017/3/24 6:33, Brian Norris wrote:
> On Thu, Mar 23, 2017 at 05:27:17PM -0500, Bjorn Helgaas wrote:
>> On Thu, Mar 09, 2017 at 06:46:13PM -0800, Brian Norris wrote:
>>> The regulator framework can return negative error codes via
>>> regulator_get_current_limit() for regulators that don't provide current
>>> information. The subsequent check for postive values isn't very useful,
>>> if the variable is unsigned.
>>>
>>> Let's just match the signedness of the return value.
>>>
>>> Prevents error messages like this, seen on Samsung Chromebook Plus:
>>>
>>> [    1.069372] rockchip-pcie f8000000.pcie: invalid power supply
>>>
>>> Fixes: 4816c4c7b82b ("PCI: rockchip: Provide captured slot power limit and scale")
>>> Signed-off-by: Brian Norris <briannorris@chromium.org>
>>> Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
>>
>> I applied the first two patches (this already has Shawn's ack and the
>> second is trivially obvious) to pci/host-rockchip.
>
> Thanks!
>
>> I'm not sure what the
>> current state of the others is.
>
> Patch 4 seems like it should be fine (it was discussed previously, but
> never done).

I'm fine with the other pacthes and fully tested it, but I was just
waiting for your decision for patch 4, so at least,

Acked-by: Shawn Lin <shawn.lin@rock-chips.com> for pcie-rockchip.


>
> Apart from existing leaks in the PCI framework (which Jeffy and Shawn
> are trying to patch [1]), I don't think there are any known issues with
> 3 and 5. It's certainly better than having 100% broken unbind at least,
> IMO.
>
> I suppose it's worth getting an ack/nack from Shawn though.
>
> Brian
>
> [1] https://patchwork.kernel.org/patch/9638353/
>     https://patchwork.kernel.org/patch/9640545/
>     https://patchwork.kernel.org/patch/9640549/
>
>
>

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