linux-kernel - Re: [PATCH 5/5] soc: qcom: llcc: Add regmap for Broadcast

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Message-ID: <CAA8EJpqa5YArFk893nDz_oibbV=oqGEeYq6_jw582rQs=O_WpA@mail.gmail.com>
Date: Tue, 30 Jan 2024 00:03:11 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Unnathi Chalicheemala <quic_uchalich@...cinc.com>
Cc: Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konrad.dybcio@...aro.org>, 
	Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, kernel@...cinc.com
Subject: Re: [PATCH 5/5] soc: qcom: llcc: Add regmap for Broadcast_AND region

On Mon, 29 Jan 2024 at 20:17, Unnathi Chalicheemala
<quic_uchalich@...cinc.com> wrote:
>
>
>
> On 1/26/2024 12:29 PM, Dmitry Baryshkov wrote:
> > On Fri, 26 Jan 2024 at 21:48, Unnathi Chalicheemala
> > <quic_uchalich@...cinc.com> wrote:
> >>
> >> To support CSR programming, a broadcast interface is used to program
> >> all channels in a single command. Until SM8450 there was only one
> >> broadcast region (Broadcast_OR) used to broadcast write and check
> >> for status bit 0. From SM8450 onwards another broadcast region
> >> (Broadcast_AND) has been added which checks for status bit 1.
> >>
> >> Update llcc_drv_data structure with new regmap for Broadcast_AND
> >> region and initialize regmap for Broadcast_AND region when HW block
> >> version is greater than 4.1 for backwards compatibility.
> >>
> >> Switch from broadcast_OR to broadcast_AND region for checking
> >> status bit 1 as Broadcast_OR region checks only for bit 0.
> >
> > This breaks backwards compatibility with the existing DT files, doesn't it?
> >
>
> It shouldn't as checking for status bit 1 is happening only when the block
> version is greater than 4.1, which is when Broadcast_AND region support
> is added.

Let me reiterate, please: with the existing DT files. You are patching
DT files in patches 2-4, but this is not enough. DT files are
considered to be ABI. As such old DT files must continue to work with
newer kernels.

>
> >> While at it, also check return value after reading Broadcast_OR
> >> region in llcc_update_act_ctrl().
> >
> > Separate patch, Fixes tag.
> >
>
> Ack. Will remove this from existing patch.
> Thanks for the review Dmitry!
>
> >>
> >> Signed-off-by: Unnathi Chalicheemala <quic_uchalich@...cinc.com>
> >> ---
> >>  drivers/soc/qcom/llcc-qcom.c       | 12 +++++++++++-
> >>  include/linux/soc/qcom/llcc-qcom.h |  4 +++-
> >>  2 files changed, 14 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/soc/qcom/llcc-qcom.c b/drivers/soc/qcom/llcc-qcom.c
> >> index 4ca88eaebf06..5a2dac2d4772 100644
> >> --- a/drivers/soc/qcom/llcc-qcom.c
> >> +++ b/drivers/soc/qcom/llcc-qcom.c
> >> @@ -849,7 +849,7 @@ static int llcc_update_act_ctrl(u32 sid,
> >>                 return ret;
> >>
> >>         if (drv_data->version >= LLCC_VERSION_4_1_0_0) {
> >> -               ret = regmap_read_poll_timeout(drv_data->bcast_regmap, status_reg,
> >> +               ret = regmap_read_poll_timeout(drv_data->bcast_and_regmap, status_reg,
> >>                                       slice_status, (slice_status & ACT_COMPLETE),
> >>                                       0, LLCC_STATUS_READ_DELAY);
> >>                 if (ret)
> >> @@ -859,6 +859,8 @@ static int llcc_update_act_ctrl(u32 sid,
> >>         ret = regmap_read_poll_timeout(drv_data->bcast_regmap, status_reg,
> >>                                       slice_status, !(slice_status & status),
> >>                                       0, LLCC_STATUS_READ_DELAY);
> >> +       if (ret)
> >> +               return ret;
> >>
> >>         if (drv_data->version >= LLCC_VERSION_4_1_0_0)
> >>                 ret = regmap_write(drv_data->bcast_regmap, act_clear_reg,
> >> @@ -1282,6 +1284,14 @@ static int qcom_llcc_probe(struct platform_device *pdev)
> >>
> >>         drv_data->version = version;
> >>
> >> +       if (drv_data->version >= LLCC_VERSION_4_1_0_0) {
> >> +               drv_data->bcast_and_regmap = qcom_llcc_init_mmio(pdev, i + 1, "llcc_broadcast_and_base");
> >> +               if (IS_ERR(drv_data->bcast_and_regmap)) {
> >> +                       ret = PTR_ERR(drv_data->bcast_and_regmap);
> >> +                       goto err;
> >> +               }
> >> +       }
> >> +
> >>         llcc_cfg = cfg->sct_data;
> >>         sz = cfg->size;
> >>
> >> diff --git a/include/linux/soc/qcom/llcc-qcom.h b/include/linux/soc/qcom/llcc-qcom.h
> >> index 1a886666bbb6..9e9f528b1370 100644
> >> --- a/include/linux/soc/qcom/llcc-qcom.h
> >> +++ b/include/linux/soc/qcom/llcc-qcom.h
> >> @@ -115,7 +115,8 @@ struct llcc_edac_reg_offset {
> >>  /**
> >>   * struct llcc_drv_data - Data associated with the llcc driver
> >>   * @regmaps: regmaps associated with the llcc device
> >> - * @bcast_regmap: regmap associated with llcc broadcast offset
> >> + * @bcast_regmap: regmap associated with llcc broadcast OR offset
> >> + * @bcast_and_regmap: regmap associated with llcc broadcast AND offset
> >>   * @cfg: pointer to the data structure for slice configuration
> >>   * @edac_reg_offset: Offset of the LLCC EDAC registers
> >>   * @lock: mutex associated with each slice
> >> @@ -129,6 +130,7 @@ struct llcc_edac_reg_offset {
> >>  struct llcc_drv_data {
> >>         struct regmap **regmaps;
> >>         struct regmap *bcast_regmap;
> >> +       struct regmap *bcast_and_regmap;
> >>         const struct llcc_slice_config *cfg;
> >>         const struct llcc_edac_reg_offset *edac_reg_offset;
> >>         struct mutex lock;
> >> --
> >> 2.25.1
> >>
> >>
> >
> >



-- 
With best wishes
Dmitry