[PATCH v3] fpga: altera-freeze-bridge: clear all illegal request bits

[PATCH v3] fpga: altera-freeze-bridge: clear all illegal request bits

[tze.yee.ng]

From: Tanmay Kathpalia <tanmay.kathpalia@altera.com>

The freeze_illegal_request register is write-1-to-clear with one bit per
Freeze Bridge connected to the Partial Reconfiguration Region Controller;
bit i is the bridge on freeze interface i. Unlike the status and control
registers, which act on all bridges collectively, this register reports
each bridge individually.

Writing a literal 1 clears only bit 0 and leaves the illegal request
latched for every other bridge. Write back the value just read instead, so
the set-to-clear applies to whichever Freeze Bridge reported the request.

Fixes: ca24a648f535 ("fpga: add altera freeze bridge support")
Cc: stable@vger.kernel.org # v4.10+

Signed-off-by: Tanmay Kathpalia <tanmay.kathpalia@altera.com>
Signed-off-by: Tze Yee Ng <tze.yee.ng@altera.com>
---
Changes in v3:
- Reword the commit message in imperative mood (Xu Yilun).
- Describe the freeze_illegal_request register layout: one write-1-to-clear
  bit per Freeze Bridge via the Conduit Merger, versus the collective
  status/ctrl registers (Xu Yilun).

Changes in v2:
- Add "Cc: stable@vger.kernel.org # v4.10+" into the signoff area so the
  stable-kernel rule is satisfied (reported by kernel test robot).
- Remove Chiau Ee's signoff as he is no longer working on this patch.

Link v2: 
https://lore.kernel.org/all/2fe34c2dec61150a39d21e067521b0acc031247c.1789956938.git.tze.yee.ng@altera.com/
---
 drivers/fpga/altera-freeze-bridge.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/fpga/altera-freeze-bridge.c b/drivers/fpga/altera-freeze-bridge.c
index c24c976117c8..2591dcc53d83 100644
--- a/drivers/fpga/altera-freeze-bridge.c
+++ b/drivers/fpga/altera-freeze-bridge.c
@@ -51,7 +51,7 @@ static int altera_freeze_br_req_ack(struct altera_freeze_br_data *priv,
 		if (illegal) {
 			dev_err(dev, "illegal request detected 0x%x", illegal);
 
-			writel(1, csr_illegal_req_addr);
+			writel(illegal, csr_illegal_req_addr);
 
 			illegal = readl(csr_illegal_req_addr);
 			if (illegal)
-- 
2.43.7

Re: Fw: [PATCH v3] fpga: altera-freeze-bridge: clear all illegal request bits

[NG, TZE YEE]

On 3/11/2026 10:31 am, NG, TZE YEE wrote:

Hi,

Gentle ping on this patch. Any chance for a review when you have time?

Thanks,
Tze Yee


> *From:* NG, TZE YEE
> *Sent:* Tuesday, October 6, 2026 10:34 AM
> *To:* Moritz Fischer <mdf@kernel.org>; Xu Yilun <yilun.xu@intel.com>; 
> Tom Rix <trix@redhat.com>; Alan Tull <atull@opensource.altera.com>; 
> Matthew Gerlach <mgerlach@opensource.altera.com>; Greg Kroah-Hartman 
> <gregkh@linuxfoundation.org>; linux-fpga@vger.kernel.org <linux- 
> fpga@vger.kernel.org>; linux-kernel@vger.kernel.org <linux- 
> kernel@vger.kernel.org>
> *Subject:* [PATCH v3] fpga: altera-freeze-bridge: clear all illegal 
> request bits
> From: Tanmay Kathpalia <tanmay.kathpalia@altera.com>
> 
> The freeze_illegal_request register is write-1-to-clear with one bit per
> Freeze Bridge connected to the Partial Reconfiguration Region Controller;
> bit i is the bridge on freeze interface i. Unlike the status and control
> registers, which act on all bridges collectively, this register reports
> each bridge individually.
> 
> Writing a literal 1 clears only bit 0 and leaves the illegal request
> latched for every other bridge. Write back the value just read instead, so
> the set-to-clear applies to whichever Freeze Bridge reported the request.
> 
> Fixes: ca24a648f535 ("fpga: add altera freeze bridge support")
> Cc: stable@vger.kernel.org # v4.10+
> 
> Signed-off-by: Tanmay Kathpalia <tanmay.kathpalia@altera.com>
> Signed-off-by: Tze Yee Ng <tze.yee.ng@altera.com>
> ---
> Changes in v3:
> - Reword the commit message in imperative mood (Xu Yilun).
> - Describe the freeze_illegal_request register layout: one write-1-to-clear
>    bit per Freeze Bridge via the Conduit Merger, versus the collective
>    status/ctrl registers (Xu Yilun).
> 
> Changes in v2:
> - Add "Cc: stable@vger.kernel.org # v4.10+" into the signoff area so the
>    stable-kernel rule is satisfied (reported by kernel test robot).
> - Remove Chiau Ee's signoff as he is no longer working on this patch.
> 
> Link v2:
> https://lore.kernel.org/ 
> all/2fe34c2dec61150a39d21e067521b0acc031247c.1789956938.git.tze.yee.ng@altera.com/ <https://lore.kernel.org/all/2fe34c2dec61150a39d21e067521b0acc031247c.1789956938.git.tze.yee.ng@altera.com/>
> ---
>   drivers/fpga/altera-freeze-bridge.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/fpga/altera-freeze-bridge.c b/drivers/fpga/altera- 
> freeze-bridge.c
> index c24c976117c8..2591dcc53d83 100644
> --- a/drivers/fpga/altera-freeze-bridge.c
> +++ b/drivers/fpga/altera-freeze-bridge.c
> @@ -51,7 +51,7 @@ static int altera_freeze_br_req_ack(struct 
> altera_freeze_br_data *priv,
>                   if (illegal) {
>                           dev_err(dev, "illegal request detected 0x%x", 
> illegal);
> 
> -                       writel(1, csr_illegal_req_addr);
> +                       writel(illegal, csr_illegal_req_addr);
> 
>                           illegal = readl(csr_illegal_req_addr);
>                           if (illegal)
> -- 
> 2.43.7
>