Re: [RFC PATCH v2 0/3] prerequisites for device reserved local mem rework

[Laurentiu Tudor]

Hi Fredrick,

On 15.05.2019 19:28, Fredrik Noring wrote:
> Hi Lauretniu,
> 
>> I think that any recent kernel will do, so I'd say your current branch
>> should be fine.
> 
> The kernel oopses with "unable to handle kernel paging request at virtual
> address 000aba0b" in hcd_alloc_coherent via usb_hcd_map_urb_for_dma. This
> relates to patch 2/3 that I didn't quite understand, where
> 
> -	retval = dma_declare_coherent_memory(dev, mem->start,
> -					 mem->start - mem->parent->start,
> -					 resource_size(mem));
> 
> becomes
> 
> +	retval = gen_pool_add_virt(hcd->localmem_pool,
> +				   (unsigned long)mem->start -
> +					mem->parent->start,
> +				   mem->start, resource_size(mem),
> 
> so that arguments two and three switch places. Given
> 
> int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
> 				dma_addr_t device_addr, size_t size);
> 
> and
> 
> int gen_pool_add_virt(struct gen_pool *pool, unsigned long virt, phys_addr_t phys
> 		 size_t size, int nid)
> 
> it seems that the device address (dma_addr_t device_addr) now becomes a
> virtual address (unsigned long virt). Is that intended?
> 
> My corresponding patch is below for reference. I applied your 1/3 patch
> to test it.

I took your code, added the missing mapping and placed it in a patch. 
Please see attached (compile tested only).

---
Thanks & Best Regards, Laurentiu
From 510c34990bbe899a2e4f43f3b904183f126f81de Mon Sep 17 00:00:00 2001
From: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>
Date: Thu, 16 May 2019 14:35:06 +0300
Subject: [PATCH] usb: host: ohci-ps2: init genalloc for local memory

In preparation for dropping the existing "coherent" dma mem declaration
APIs, replace the current dma_declare_coherent_memory() based mechanism
with the creation of a genalloc pool that will be used in the OHCI
subsystem as replacement for the DMA APIs.

For context, see thread here: https://lkml.org/lkml/2019/4/22/357

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>
---
 drivers/usb/host/ohci-ps2.c | 44 ++++++++++++++++++++++++++-----------
 1 file changed, 31 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/host/ohci-ps2.c b/drivers/usb/host/ohci-ps2.c
index 7669b7358bc3..454e5e3ac96e 100755
--- a/drivers/usb/host/ohci-ps2.c
+++ b/drivers/usb/host/ohci-ps2.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/dma-mapping.h>
+#include <linux/genalloc.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/usb.h>
@@ -92,12 +93,13 @@ static irqreturn_t ohci_ps2_irq(struct usb_hcd *hcd)
 	return ohci_irq(hcd); /* Call normal IRQ handler. */
 }
 
-static int iopheap_alloc_coherent(struct platform_device *pdev,
-	size_t size, int flags)
+static int iopheap_alloc_coherent(struct platform_device *pdev, size_t size)
 {
 	struct device *dev = &pdev->dev;
 	struct usb_hcd *hcd = platform_get_drvdata(pdev);
 	struct ps2_hcd *ps2priv = hcd_to_priv(hcd);
+	void __iomem *local_mem;
+	int err;
 
 	if (ps2priv->iop_dma_addr != 0)
 		return 0;
@@ -112,28 +114,45 @@ static int iopheap_alloc_coherent(struct platform_device *pdev,
 		return -ENOMEM;
 	}
 
-	if (dma_declare_coherent_memory(dev,
-			iop_bus_to_phys(ps2priv->iop_dma_addr),
-			ps2priv->iop_dma_addr, size, flags)) {
-		dev_err(dev, "dma_declare_coherent_memory failed\n");
-		iop_free(ps2priv->iop_dma_addr);
-		ps2priv->iop_dma_addr = 0;
-		return -ENOMEM;
+	hcd->localmem_pool = devm_gen_pool_create(dev, PAGE_SHIFT,
+						  dev_to_node(dev), DRV_NAME);
+	if (IS_ERR(hcd->localmem_pool)) {
+		err = PTR_ERR(hcd->localmem_pool);
+		goto out_err;
+	}
+
+	local_mem = devm_ioremap(dev,
+				 iop_bus_to_phys(ps2priv->iop_dma_addr),
+				 size);
+	if (!local_mem) {
+		err = -ENOMEM;
+		goto out_err;
+	}
+
+	err = gen_pool_add_virt(hcd->localmem_pool, (unsigned long)local_mem,
+				ps2priv->iop_dma_addr, size, dev_to_node(dev));
+	if (err < 0) {
+		dev_err(dev, "gen_pool_add_virt failed with %d\n", err);
+		goto out_err;
 	}
 
 	return 0;
+
+out_err:
+	iop_free(ps2priv->iop_dma_addr);
+	ps2priv->iop_dma_addr = 0;
+
+	return err;
 }
 
 static void iopheap_free_coherent(struct platform_device *pdev)
 {
-	struct device *dev = &pdev->dev;
 	struct usb_hcd *hcd = platform_get_drvdata(pdev);
 	struct ps2_hcd *ps2priv = hcd_to_priv(hcd);
 
 	if (ps2priv->iop_dma_addr == 0)
 		return;
 
-	dma_release_declared_memory(dev);
 	iop_free(ps2priv->iop_dma_addr);
 	ps2priv->iop_dma_addr = 0;
 }
@@ -177,8 +196,7 @@ static int ohci_hcd_ps2_probe(struct platform_device *pdev)
 		goto err;
 	}
 
-	ret = iopheap_alloc_coherent(pdev,
-		DMA_BUFFER_SIZE, DMA_MEMORY_EXCLUSIVE);
+	ret = iopheap_alloc_coherent(pdev, DMA_BUFFER_SIZE);
 	if (ret != 0)
 		goto err_alloc_coherent;
 
-- 
2.17.1