Re: [PATCH v1 1/2] bus: mhi: core: Bail on writing register fields if read fails

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Wed, Aug 18, 2021 at 04:50:33PM -0700, Bhaumik Bhatt wrote:
> Helper API to write register fields relies on successful reads
> of the register/address prior to the write. Bail out if a failure
> is seen when reading the register before the actual write is
> performed.
> 
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>

As spotted by the test bot, can you please update pm.c as well?

Thanks,
Mani

> ---
>  drivers/bus/mhi/core/boot.c     | 25 +++++++++++++++++--------
>  drivers/bus/mhi/core/init.c     | 24 ++++++++++++++++++------
>  drivers/bus/mhi/core/internal.h |  7 ++++---
>  drivers/bus/mhi/core/main.c     |  9 ++++++---
>  4 files changed, 45 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/boot.c b/drivers/bus/mhi/core/boot.c
> index 0a97262..13eacda 100644
> --- a/drivers/bus/mhi/core/boot.c
> +++ b/drivers/bus/mhi/core/boot.c
> @@ -19,8 +19,8 @@
>  #include "internal.h"
>  
>  /* Setup RDDM vector table for RDDM transfer and program RXVEC */
> -void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
> -		      struct image_info *img_info)
> +int mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
> +		     struct image_info *img_info)
>  {
>  	struct mhi_buf *mhi_buf = img_info->mhi_buf;
>  	struct bhi_vec_entry *bhi_vec = img_info->bhi_vec;
> @@ -28,6 +28,7 @@ void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
>  	u32 sequence_id;
>  	unsigned int i;
> +	int ret;
>  
>  	for (i = 0; i < img_info->entries - 1; i++, mhi_buf++, bhi_vec++) {
>  		bhi_vec->dma_addr = mhi_buf->dma_addr;
> @@ -45,12 +46,17 @@ void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
>  	mhi_write_reg(mhi_cntrl, base, BHIE_RXVECSIZE_OFFS, mhi_buf->len);
>  	sequence_id = MHI_RANDOM_U32_NONZERO(BHIE_RXVECSTATUS_SEQNUM_BMSK);
>  
> -	mhi_write_reg_field(mhi_cntrl, base, BHIE_RXVECDB_OFFS,
> -			    BHIE_RXVECDB_SEQNUM_BMSK, BHIE_RXVECDB_SEQNUM_SHFT,
> -			    sequence_id);
> +	ret = mhi_write_reg_field(mhi_cntrl, base, BHIE_RXVECDB_OFFS,
> +				  BHIE_RXVECDB_SEQNUM_BMSK,
> +				  BHIE_RXVECDB_SEQNUM_SHFT, sequence_id);
> +	if (ret) {
> +		dev_err(dev, "Failed to write sequence ID for BHIE_RXVECDB\n");
> +		return ret;
> +	}
>  
>  	dev_dbg(dev, "Address: %p and len: 0x%zx sequence: %u\n",
>  		&mhi_buf->dma_addr, mhi_buf->len, sequence_id);
> +	return 0;
>  }
>  
>  /* Collect RDDM buffer during kernel panic */
> @@ -202,11 +208,14 @@ static int mhi_fw_load_bhie(struct mhi_controller *mhi_cntrl,
>  
>  	mhi_write_reg(mhi_cntrl, base, BHIE_TXVECSIZE_OFFS, mhi_buf->len);
>  
> -	mhi_write_reg_field(mhi_cntrl, base, BHIE_TXVECDB_OFFS,
> -			    BHIE_TXVECDB_SEQNUM_BMSK, BHIE_TXVECDB_SEQNUM_SHFT,
> -			    sequence_id);
> +	ret = mhi_write_reg_field(mhi_cntrl, base, BHIE_TXVECDB_OFFS,
> +				  BHIE_TXVECDB_SEQNUM_BMSK,
> +				  BHIE_TXVECDB_SEQNUM_SHFT, sequence_id);
>  	read_unlock_bh(pm_lock);
>  
> +	if (ret)
> +		return ret;
> +
>  	/* Wait for the image download to complete */
>  	ret = wait_event_timeout(mhi_cntrl->state_event,
>  				 MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state) ||
> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> index 5aaca6d..0917465 100644
> --- a/drivers/bus/mhi/core/init.c
> +++ b/drivers/bus/mhi/core/init.c
> @@ -544,10 +544,15 @@ int mhi_init_mmio(struct mhi_controller *mhi_cntrl)
>  	mhi_cntrl->mhi_cmd[PRIMARY_CMD_RING].ring.db_addr = base + CRDB_LOWER;
>  
>  	/* Write to MMIO registers */
> -	for (i = 0; reg_info[i].offset; i++)
> -		mhi_write_reg_field(mhi_cntrl, base, reg_info[i].offset,
> -				    reg_info[i].mask, reg_info[i].shift,
> -				    reg_info[i].val);
> +	for (i = 0; reg_info[i].offset; i++) {
> +		ret = mhi_write_reg_field(mhi_cntrl, base, reg_info[i].offset,
> +					  reg_info[i].mask, reg_info[i].shift,
> +					  reg_info[i].val);
> +		if (ret) {
> +			dev_err(dev, "Unable to write to MMIO registers");
> +			return ret;
> +		}
> +	}
>  
>  	return 0;
>  }
> @@ -1118,8 +1123,15 @@ int mhi_prepare_for_power_up(struct mhi_controller *mhi_cntrl)
>  		 */
>  		mhi_alloc_bhie_table(mhi_cntrl, &mhi_cntrl->rddm_image,
>  				     mhi_cntrl->rddm_size);
> -		if (mhi_cntrl->rddm_image)
> -			mhi_rddm_prepare(mhi_cntrl, mhi_cntrl->rddm_image);
> +		if (mhi_cntrl->rddm_image) {
> +			ret = mhi_rddm_prepare(mhi_cntrl,
> +					       mhi_cntrl->rddm_image);
> +			if (ret) {
> +				mhi_free_bhie_table(mhi_cntrl,
> +						    mhi_cntrl->rddm_image);
> +				goto error_reg_offset;
> +			}
> +		}
>  	}
>  
>  	mutex_unlock(&mhi_cntrl->pm_mutex);
> diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
> index 721739c..3d17ec3 100644
> --- a/drivers/bus/mhi/core/internal.h
> +++ b/drivers/bus/mhi/core/internal.h
> @@ -663,8 +663,9 @@ int __must_check mhi_poll_reg_field(struct mhi_controller *mhi_cntrl,
>  				    u32 shift, u32 val, u32 delayus);
>  void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
>  		   u32 offset, u32 val);
> -void mhi_write_reg_field(struct mhi_controller *mhi_cntrl, void __iomem *base,
> -			 u32 offset, u32 mask, u32 shift, u32 val);
> +int __must_check mhi_write_reg_field(struct mhi_controller *mhi_cntrl,
> +				     void __iomem *base, u32 offset,
> +				     u32 mask, u32 shift, u32 val);
>  void mhi_ring_er_db(struct mhi_event *mhi_event);
>  void mhi_write_db(struct mhi_controller *mhi_cntrl, void __iomem *db_addr,
>  		  dma_addr_t db_val);
> @@ -678,7 +679,7 @@ int mhi_init_dev_ctxt(struct mhi_controller *mhi_cntrl);
>  void mhi_deinit_dev_ctxt(struct mhi_controller *mhi_cntrl);
>  int mhi_init_irq_setup(struct mhi_controller *mhi_cntrl);
>  void mhi_deinit_free_irq(struct mhi_controller *mhi_cntrl);
> -void mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
> +int mhi_rddm_prepare(struct mhi_controller *mhi_cntrl,
>  		      struct image_info *img_info);
>  void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl);
>  int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index c01ec2f..902d854 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -66,19 +66,22 @@ void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
>  	mhi_cntrl->write_reg(mhi_cntrl, base + offset, val);
>  }
>  
> -void mhi_write_reg_field(struct mhi_controller *mhi_cntrl, void __iomem *base,
> -			 u32 offset, u32 mask, u32 shift, u32 val)
> +int __must_check mhi_write_reg_field(struct mhi_controller *mhi_cntrl,
> +				     void __iomem *base, u32 offset,
> +				     u32 mask, u32 shift, u32 val)
>  {
>  	int ret;
>  	u32 tmp;
>  
>  	ret = mhi_read_reg(mhi_cntrl, base, offset, &tmp);
>  	if (ret)
> -		return;
> +		return ret;
>  
>  	tmp &= ~mask;
>  	tmp |= (val << shift);
>  	mhi_write_reg(mhi_cntrl, base, offset, tmp);
> +
> +	return 0;
>  }
>  
>  void mhi_write_db(struct mhi_controller *mhi_cntrl, void __iomem *db_addr,
> -- 
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>